Processing method

Abstract

To provide a processing method capable of suppressing the generation of an end material without using a processing device with a special mechanism.SOLUTION: A processing method includes: an annular groove forming step 101 in which an annular groove is formed from the front surface side of a wafer along an outer peripheral edge of the wafer to a predetermined thickness, and a remaining portion is formed below the annular groove, the annular groove being formed such that the groove bottom approaches the rear surface side from the center side of the wafer toward the outer peripheral edge side of the wafer, and the position of the groove bottom in the thickness direction of the wafer varies in the width direction; and a grinding step 103 in which a grinding stone is brought into contact with the rear surface of the wafer after the annular groove forming step 101, and the grinding stone is fed in the thickness direction of the wafer to grind the rear surface side of the wafer, the remaining portion is crushed and removed and the wafer is thinned to a predetermined thickness.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for processing a wafer having a chamfered portion formed on its outer periphery. [Background technology]

[0002] 2. Description of the Related Art In order to prevent edge chipping when a semiconductor wafer is ground by a grinding device, so-called edge trimming, in which a chamfered portion of a semiconductor wafer is trimmed, is widely practiced.

[0003] However, when edge-trimmed wafers are ground by a grinding machine, the outer periphery of the trimmed wafer breaks and arc-shaped scraps fall from the wafer, causing a problem that the scraps accumulate in the drainage port in the processing chamber, known as the water case of the grinding machine, and impede the discharge of processing water.

[0004] In view of this, a processing device has been proposed that includes a mechanism capable of crushing scraps and suppressing the generation of scraps (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-109278 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is a strong demand for a method that can suppress the generation of scraps without using processing equipment with special mechanisms.

[0007] An object of the present invention is to provide a processing method capable of suppressing the generation of scrap material without using a processing device with a special mechanism. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a processing method of the present invention is a processing method for grinding a second surface of a wafer having a first surface and a second surface behind the first surface, with a chamfered portion formed on an outer periphery, to thin the wafer to a predetermined thickness, the processing method comprising: an annular groove forming step of forming an annular groove from the first surface side of the wafer along the outer periphery of the wafer to the predetermined thickness and forming a remaining portion below the annular groove; and a grinding step of, after performing the annular groove forming step, bringing a grinding wheel into contact with the second surface of the wafer and feeding the grinding wheel in the thickness direction of the wafer to grind the second surface side of the wafer while crushing and removing the remaining portion, thereby thinning the wafer to the predetermined thickness.

[0009] In the above processing method, in the annular groove forming step, the wafer may be cut with a cutting blade having a first surface and a second surface behind the first surface, the diameter of the second surface side being set to a value larger than the diameter of the first surface side, and a cutting blade with a one-sided V-shaped tip cross section.

[0010] In the above processing method, in the annular groove forming step, cutting may be performed with a cutting blade at different positions in a width direction of the annular groove with different cutting depths. Effect of the Invention

[0011] The present invention has an effect of suppressing the generation of scraps without using a processing device with a special mechanism. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an example of a wafer to be processed by the processing method according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a flowchart showing the flow of the processing method according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view that typically illustrates the annular groove forming step of the processing method illustrated in FIG. [Diagram 5] FIG. 5 is a cross-sectional view of the outer edge of the cutting blade shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view showing a schematic diagram of a wafer after a surface protection step in the processing method shown in FIG. [Figure 7] FIG. 7 is a side view, partially in section, showing a schematic diagram of a state immediately after start of grinding in the grinding step of the processing method shown in FIG. [Figure 8] FIG. 8 is an enlarged, partially sectional side view showing a schematic view of a portion VIII shown in FIG. [Figure 9] FIG. 9 is a side view, partially in section, that typically illustrates a state in which the remaining portion is ground in the grinding step of the processing method illustrated in FIG. [Figure 10] FIG. 10 is a side view, partially in section, that typically shows a state in which the wafer has been ground to a predetermined thickness in the grinding step of the processing method shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view that illustrates a state in which a first annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. [Figure 12] FIG. 12 is a cross-sectional view that illustrates a state in which a second annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view that typically illustrates a state in which a third annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view that typically shows a wafer etc. on which an annular groove has been formed in the annular groove forming step of the processing method according to the second embodiment. [Figure 15] FIG. 15 is a side view, partially in section, illustrating a grinding step of the processing method according to the second embodiment. [Figure 16] FIG. 16 is a cross-sectional view that illustrates a schematic annular groove forming step of the processing method according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0014] [Embodiment 1] A processing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of a wafer to be processed by the processing method according to the first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a flow chart showing the flow of the processing method according to the first embodiment.

[0015] (Workpiece) The processing method according to the first embodiment is a method for thinning the wafer 1 shown in Fig. 1. The wafer 1 to be processed by the processing method according to the first embodiment is, for example, a disk-shaped semiconductor wafer having a silicon substrate 2, a front surface 3 (corresponding to a first surface), and a back surface 6 (corresponding to a second surface) behind the front surface 3. Note that in the present invention, the wafer 1 is not limited to silicon, and may be a disk-shaped semiconductor wafer or an optical device wafer having a substrate 2 made of gallium arsenide, sapphire, SiC, lithium tantalate, lithium niobate, or the like.

[0016] As shown in FIG. 1, a wafer 1 has a plurality of planned division lines 4 that intersect with each other set on a surface 3 of a substrate 2, and devices 5 are formed in areas defined by the planned division lines 4 on the surface 3 of the substrate 2.

[0017] The device 5 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), an optical element such as an LED (Light-Emitting Diode), or a memory (semiconductor memory device).

[0018] 2, the wafer 1 has a chamfered portion 7 formed on its outer periphery. The chamfered portion 7 is formed from the front surface 3 to the back surface 6, and is formed in an arc-shaped cross section such that the center in the thickness direction is located at the outermost side. The outer peripheral edge of the wafer 1 is removed from the front surface 3 side all around the circumference to a depth exceeding a predetermined thickness 8, and then the back surface 6 side is ground or otherwise thinned to the predetermined thickness 8. The wafer 1 is then divided into individual devices 5 along the planned division lines 4.

[0019] (Processing method) The processing method according to the first embodiment is a method for grinding the back surface 6 of the wafer 1 to thin it to a predetermined thickness 8. As shown in Fig. 3, the processing method according to the first embodiment includes an annular groove forming step 101, a surface protection step 102, and a grinding step 103.

[0020] (Annular groove forming step) Fig. 4 is a cross-sectional view showing a schematic annular groove forming step of the processing method shown in Fig. 3. Fig. 5 is a cross-sectional view of the outer edge of the cutting blade shown in Fig. 4. The annular groove forming step 101 is a step of forming an annular groove 10 extending from the front surface 3 side of the wafer 1 along the outer periphery of the wafer 1 to a predetermined thickness 8, and forming a remaining portion 11 below the annular groove 10.

[0021] 4 suction-holds the back surface 9 side of the wafer 1 on the holding surface 32 of the chuck table 31. In the first embodiment, in the annular groove forming step 101, the cutting device 30 rotates the cutting blade 35 around its axis by the spindle 34, positions the lower end of the cutting blade 35 above the outer circumferential edge of the wafer 1, and then lowers the cutting unit 33.

[0022] In the first embodiment, in the annular groove forming step 101, the cutting device 30 cuts the cutting blade 35 into the outer peripheral edge of the wafer 1 to a depth exceeding a predetermined thickness 8, and rotates the chuck table 31 around its axis, as shown in Fig. 4. In the first embodiment, in the annular groove forming step 101, the cutting device 30 removes the chamfered portion 7 of the wafer 1 in an annular shape from the front surface 3 side to form an annular groove 10 coaxial with the wafer 1 along the outer peripheral edge to a depth exceeding the predetermined thickness 8 all around the wafer 1, and also forms a remaining portion 11 below the back surface 6 side of the annular groove 10.

[0023] In the first embodiment, in the annular groove forming step 101, the outer peripheral edge of the wafer 1 is cut all around with a ring-shaped cutting blade 35 having a flat first surface 36 perpendicular to the axis and a flat second surface 37 that is on the back side of the first surface 36 and parallel to the first surface 36 and is disposed on the outer peripheral side of the wafer 1 relative to the first surface 36, and the chamfered portion 7 is removed all around from the front surface 3 side. In the first embodiment, the cutting blade 35 that cuts the wafer 1 in the annular groove forming step 101 is set so that the diameter on the second surface 37 side is set to a value larger than the diameter on the first surface 36 side, and as shown in FIG. 5, in a cross section passing through the axis, the cross section of the outer peripheral surface 38, which is the tip, is inclined with respect to the axis of the cutting blade 35 in a direction in which the outer diameter increases toward the second surface 37, forming a one-sided V shape.

[0024] In the first embodiment, the cutting blade 35 that cuts the wafer 1 in the annular groove forming step 101 is formed such that, in a cross section passing through the axis, the angle θ1 (hereinafter referred to as the inclination angle) of the outer peripheral surface 38 with respect to the axis is 4 degrees or more and 9 degrees or less, and the angle θ2 (hereinafter referred to as the tip angle) of the outer peripheral surface 38 with respect to the second surface 37 is 81 degrees or more and 86 degrees or less. In the first embodiment, the cutting blade 35 that cuts the wafer 1 in the annular groove forming step 101 is formed such that the second surface 37 is positioned on the outer peripheral side and above the outer peripheral edge of the wafer 1, and then the first surface 36 is lowered deeper than the predetermined thickness 8 to cut into the wafer 1.

[0025] For this reason, in the first embodiment, the annular groove 10 formed in the annular groove forming step 101 is formed so that the distance between the groove bottom 12 and the back surface 6 decreases from the center side of the wafer 1 toward the outer periphery side of the wafer 1, and the position of the groove bottom 12 in the thickness direction of the wafer 1 varies in the width direction. That is, the annular groove 10 is inclined with respect to the horizontal direction (i.e., both the front surface 3 and the back surface 6) so that the groove bottom 12 gradually approaches the back surface 6 from the center side of the wafer 1 toward the outer periphery.

[0026] Thus, in the first embodiment, in the annular groove forming step 101, the cutting device 30 lowers the cutting blade 35 positioned above the chamfered portion 7 of the wafer 1, so that the cutting blade 35 cuts into the wafer 1 at a position including the outer periphery, and the wafer 1 is rotated around its axis on the chuck table 31 by a so-called chopper cut, so that the outer periphery of the wafer 1 is removed from the front surface 3 side by so-called edge trimming, thereby forming the annular groove 10. However, in the present invention, the annular groove forming step 101 may be performed by the cutting device 30 moving the cutting blade 35, the lower end of which is positioned below the front surface 3 by a predetermined thickness 8, in a horizontal direction relative to the wafer 1 to cut into the wafer 1, and rotating the wafer 1 around its axis on the chuck table 31 to perform edge trimming to remove the outer periphery of the wafer 1 from the front surface 3 side, thereby forming the annular groove 10.

[0027] (Surface protection step) Fig. 6 is a cross-sectional view showing a schematic diagram of the wafer after the surface protection step of the processing method shown in Fig. 3. The surface protection step 102 is a step of providing a tape 20, which is a protective member, on the surface 3 of the wafer 1.

[0028] In the first embodiment, in the surface protection step 102, a tape 20 having the same diameter as the wafer 1 is attached to the surface 3 of the wafer 1, as shown in Fig. 6. In the first embodiment, the tape 20 is used as the protective member, but in the present invention, the protective member is not limited to the tape 20.

[0029] In the first embodiment, the tape 20 is an adhesive tape including a base layer made of a non-adhesive and flexible resin and an adhesive layer made of an adhesive and flexible resin laminated on the base layer, the adhesive layer being attached to the surface 3 of the wafer 1. In the present invention, the tape 20 may be a sheet that does not include an adhesive layer and is made of only a base material made of a thermoplastic resin, and is attached to the surface 3 of the wafer 1 by heating.

[0030] (Grinding step) Fig. 7 is a side view, partially in section, showing a state immediately after grinding starts in the grinding step of the processing method shown in Fig. 3. Fig. 8 is a side view, partially in section, showing an enlarged schematic view of part VIII shown in Fig. 7. Fig. 9 is a side view, partially in section, showing a state in which a remaining part is ground in the grinding step of the processing method shown in Fig. 3. Fig. 10 is a side view, partially in section, showing a state in which the wafer has been ground to a predetermined thickness in the grinding step of the processing method shown in Fig. 3.

[0031] In the grinding step 103, after the annular groove forming step 101 is performed, a grinding wheel 55 is brought into contact with the back surface 6 of the wafer 1 and the grinding wheel 55 is fed in the thickness direction of the wafer 1 to grind the back surface 6 side of the wafer 1 while pulverizing and removing the remaining portion 11, thereby thinning the wafer 1 to a predetermined thickness 8. In the first embodiment, in the grinding step 103, the grinding device 50 suction-holds the front surface 3 side of the wafer 1 on the holding surface 52 of the holding table 51 via the tape 20.

[0032] In the first embodiment, in the grinding step 103, the grinding device 50 rotates the holding table 51 around an axis parallel to the vertical direction while rotating the grinding wheel 54 of the grinding unit 53 around an axis parallel to the vertical direction, as shown in Fig. 7 and Fig. 8, to bring the grinding stone 55 of the grinding wheel 54 into contact with the back surface 6 of the wafer 1, and feeds the grinding unit 53 toward the front surface 3 of the wafer 1 to grind the back surface 6 side with the grinding stone 55. Then, the grinding device 50 gradually grinds the remaining portion 11 with the grinding stone 55 as shown in Fig. 9.

[0033] In the first embodiment, in the grinding step 103, since the groove bottom 12 of the annular groove 10 is gradually inclined in a direction approaching the back surface 6 toward the outer periphery, the grinding wheel 55 gradually grinds and removes the remaining portion 11 from the outer periphery toward the center of the wafer 1. In the first embodiment, in the grinding step 103, the grinding device 50 thins the wafer 1 to a predetermined thickness 8 as shown in Fig. 10, and when the wafer 1 is thinned to the predetermined thickness 8, the processing method is terminated. Then, since the annular groove 10 is formed to a depth exceeding the predetermined thickness 8 from the front surface 3, the remaining portion 11, i.e., the entire chamfered portion 7, is removed from the outer periphery of the wafer 1.

[0034] The processing method according to the first embodiment described above forms an annular groove 10 in annular groove forming step 101 in which the distance between the groove bottom 12 and the back surface 6 side decreases from the center side of the wafer 1 toward the outer periphery side, and the position of the groove bottom 12 in the thickness direction of the wafer 1 varies in the width direction. For this reason, in the processing method according to the first embodiment, the remaining portion 11 is gradually removed from the outer periphery side toward the center of the wafer 1 in the grinding step 103. Therefore, the processing method according to the first embodiment can suppress the risk of waste material being generated after processing.

[0035] As a result, the processing method of embodiment 1 merely forms an annular groove 10 whose groove bottom 12 approaches the back surface 6 for removal as it moves toward the outer peripheral edge, thereby achieving the effect of suppressing the generation of scrap material without using processing equipment with a special mechanism.

[0036] [Embodiment 2] The processing method according to the second embodiment will be described with reference to the drawings. FIG. 11 is a cross-sectional view showing a state where a first annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. FIG. 12 is a cross-sectional view showing a state where a second annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. FIG. 13 is a cross-sectional view showing a state where a third annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. FIG. 14 is a cross-sectional view showing a wafer or the like on which an annular groove is formed in the annular groove forming step of the processing method according to the second embodiment. FIG. 15 is a side view showing a grinding step of the processing method according to the second embodiment in a partial cross section. In addition, in FIGS. 11, 12, 13, 14, and 15, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0037] The processing method according to the second embodiment is the same as that according to the first embodiment, except that the annular groove forming step 101 is different. In the second embodiment, in the annular groove forming step 101, in a cross section passing through the axis, the outer peripheral surface 38 of the cutting blade 35-2 of the cutting device 30 that cuts the outer peripheral edge of the wafer 1 is flat along the axis. In the second embodiment, in the annular groove forming step 101, the cutting device 30 suction-holds the back surface 6 of the wafer 1 on the holding surface 32 of the chuck table 31, and then positions the second surface 37 of the cutting blade 35-2 on the inner side of the outer peripheral edge of the wafer 1, and then cuts the cutting blade 35-2 into the wafer 1 to a depth exceeding a predetermined thickness 8, and forms a first annular groove 13 coaxial with the wafer 1 at a depth exceeding the predetermined thickness 8 along the outer peripheral edge of the wafer 1 around the entire circumference of the wafer 1, as shown in FIG.

[0038] In embodiment 2, in the annular groove forming step 101, after the cutting device 30 forms the first annular groove 13 in the wafer 1, the cutting blade 35-2 is positioned closer to the outer periphery of the wafer 1 than when the first annular groove 13 was formed, and the cutting blade 35-2 is caused to cut deeper into the wafer 1 than when the first annular groove 13 was formed, to form a second annular groove 14 along the outer periphery of the wafer 1 to a depth exceeding a predetermined thickness 8, as shown in FIG. 12, which is coaxial with the wafer 1 and communicates with the first annular groove 13, around the entire circumference of the wafer 1. In embodiment 2, in the annular groove forming step 101, after the cutting device 30 forms the second annular groove 14 in the wafer 1, the cutting blade 35-2 is positioned closer to the outer periphery of the wafer 1 than when the second annular groove 14 was formed, and the cutting blade 35-2 is caused to cut deeper into the wafer 1 than when the second annular groove 14 was formed, to form a third annular groove 15 along the outer periphery of the wafer 1 to a depth exceeding a predetermined thickness 8, as shown in FIG. 13, which is coaxial with the wafer 1 and communicates with the annular grooves 13 and 14, around the entire circumference of the wafer 1.

[0039] Thus, in the annular groove forming step 101 in the second embodiment, the cutting device 30 removes the chamfered portion 7 of the wafer 1 from the front surface 3 side in an annular shape, forms an annular groove 10-2 along the entire circumference of the wafer 1, which is coaxial with the wafer 1 and is composed of annular grooves 13, 14, 15 that communicate with each other and have a depth exceeding a predetermined thickness 8 along the outer periphery, and forms a remaining portion 11 below the back surface 6 side of the annular groove 10-2. Thus, in the annular groove forming step 101 in the second embodiment, the cutting device 30 cuts the wafer 1 multiple times with the cutting blade 35-2, and cuts different positions in the width direction of the annular groove 10-2 with different cutting depths with the cutting blade 35-2, to form a stepped annular groove 10 in which the groove bottom 12-2 approaches the back surface 6 side from the center side of the wafer 1 toward the outer periphery side of the wafer 1.

[0040] In the second embodiment, in the annular groove forming step 101, the cutting device 30 forms the three annular grooves 13, 14, and 15 to form the annular groove 10-2, but in the present invention, it is sufficient to form the annular groove 10-2 by forming at least two annular grooves 13, 14, and 15. In the second embodiment, the cutting blade 35-2 may have a blade thickness thinner than the width of the annular groove 10-2 to be formed, may have the same blade thickness, or may have a blade thickness thicker than the width of the annular groove 10-2 to be formed.

[0041] In embodiment 2, in the grinding step 103, a grinding device 50 holds the front surface 3 side of the wafer 1 on a holding surface 52 of a holding table 51 via a tape 20, and grinds the back surface 6 as shown in FIG. 15 to thin the wafer 1 to a predetermined thickness 8.

[0042] The processing method according to the second embodiment forms an annular groove 10-2 in an annular groove forming step 101 in which the groove bottom 12-2 approaches the back surface 6 from the center side of the wafer 1 toward the outer periphery side and the position of the groove bottom 12-2 in the thickness direction of the wafer 1 varies in the width direction. As a result, the processing method according to the second embodiment only forms an annular groove 10-2 in which the groove bottom 12-2 approaches the back surface 6 as it approaches the outer periphery, as in the first embodiment, by which the remaining portion 11 is gradually removed from the outer periphery side toward the center of the wafer 1 in the grinding step 103. This has the effect of suppressing the generation of waste materials without using a processing device with a special mechanism.

[0043] [Embodiment 3] The processing method according to the third embodiment will be described with reference to the drawings. Fig. 16 is a cross-sectional view that shows a schematic annular groove forming step of the processing method according to the third embodiment. In Fig. 16, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0044] The processing method according to the third embodiment is the same as that according to the first embodiment, except that the annular groove forming step 101 is different. In the third embodiment, in the annular groove forming step 101, the outer peripheral surface 38 of the cutting blade 35-3 that cuts the outer peripheral edge of the wafer 1 of the cutting device 30 is flat along the axis in a cross section passing through the axis. In the third embodiment, in the annular groove forming step 101, the cutting device 30 suction-holds the back surface 6 of the wafer 1 on the holding surface 32 of the chuck table 31, and then positions the second surface 37 of the cutting blade 35-3 on the inner peripheral side of the outer peripheral edge of the wafer 1, and then cuts the cutting blade 35-3 into the wafer 1 to a depth exceeding a predetermined thickness 8, and as shown in FIG. 16, the cutting blade 35-3 is moved closer to the back surface 6 side and toward the outer periphery of the wafer 1 while rotating the chuck table 31 around the axis, thereby forming an annular groove 10 having a shape equivalent to that of the first embodiment.

[0045] The processing method according to the third embodiment forms an annular groove 10 in an annular groove forming step 101 in which the groove bottom 12 approaches the back surface 6 from the center side of the wafer 1 toward the outer periphery side and the position of the groove bottom 12 in the thickness direction of the wafer 1 varies in the width direction. As a result, the processing method according to the third embodiment only forms an annular groove 10 in which the groove bottom 12 approaches the back surface 6 as it approaches the outer periphery, as in the first embodiment, by gradually removing the remaining portion 11 from the outer periphery side toward the center of the wafer 1. This has the effect of suppressing the generation of waste materials without using a processing device with a special mechanism.

[0046] Next, the inventors of the present invention confirmed the effect of the processing method according to embodiment 1. The results are shown in Table 1 below. In the confirmation, the annular groove 10 was formed on the outer periphery of the wafer 1 with the cutting blade 35 of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Inventive Product 1, Inventive Product 2, Inventive Product 3, Inventive Product 4, Inventive Product 5, and Inventive Product 6, and the falling state of the end material when grinding step 103 was performed and the chipping after processing were confirmed.

[0047] In Table 1, the chipping status of scraps that fell during or after grinding step 103 is marked with a cross, and the chipping status of scraps that did not fall during or after grinding step 103 is marked with a circle. Also, in Table 1, the chipping status of scraps that had the number and size of chippings after processing below a predetermined number is marked with a circle, and the chipping status of scraps that had the number and size of chippings after processing exceeding a predetermined number is marked with an cross.

[0048] [Table 1]

[0049] In Comparative Example 1, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 0 degrees. In Comparative Example 2, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 1 degree. In Comparative Example 3, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 2 degrees. In Comparative Example 4, the cutting depth of the annular groove forming step 101 was deeper, and the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 3 degrees. In Comparative Example 5, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 10 degrees.

[0050] In product 1 of the present invention, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 4 degrees. In product 2 of the present invention, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 5 degrees. In product 3 of the present invention, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 6 degrees. In product 4 of the present invention, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 7 degrees. In product 5 of the present invention, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 8 degrees. In product 6 of the present invention, the annular groove 10 was formed with a cutting blade 35 with an inclination angle θ1 of 9 degrees.

[0051] According to Table 1, in Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, scraps fell off during or after the grinding step 103. In Comparative Example 5, the cutting depth in the annular groove forming step 101 became deep, and the number and size of chippings after processing exceeded the specified number.

[0052] In contrast to Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5, in the present invention products 1, 2, 3, 4, 5 and 6, there was no falling of scraps during or after the grinding step 103, and the number and size of chipping after processing was below the specified number.

[0053] Therefore, according to Table 1, it is clear that by forming the annular groove 10 with a cutting blade 35 having an inclination angle θ1 of 1 degree or more and 9 degrees or less, it is possible to suppress chipping after processing while also suppressing the generation of scrap material without using processing equipment with a special mechanism.

[0054] It should be noted that the present invention is not limited to the above-described embodiment, and can be practiced in various modified forms without departing from the gist of the present invention. [Explanation of symbols]

[0055] 1 wafer 3 Surface (first side) 6 Back side (2nd side) 7 Chamfer 8. Prescribed thickness 10,10-2 Annular groove 11 Remaining part 12,12-2 Groove bottom 35,35-2,35-3 Cutting blade 36 Page 1 37 2nd page 55 Grinding Wheel 101 Annular groove forming step 103 Grinding Step

Claims

1. A processing method for thinning a wafer having a first surface and a second surface behind the first surface, the second surface having a chamfered portion formed on an outer periphery thereof, by grinding the second surface to a predetermined thickness, comprising the steps of: an annular groove forming step of forming an annular groove from the first surface side of the wafer along an outer periphery of the wafer to the predetermined thickness and forming a remaining portion below the annular groove; the annular groove is formed such that the distance between the bottom of the groove and the second surface side decreases from the center side of the wafer toward the outer peripheral edge side of the wafer, and the position of the bottom of the groove in the thickness direction of the wafer varies in the width direction; and a grinding step in which, after performing the annular groove forming step, a grinding wheel is brought into contact with the second surface of the wafer and the grinding wheel is moved in a thickness direction of the wafer to grind the second surface side of the wafer while pulverizing and removing the remaining portion, thereby thinning the wafer to the predetermined thickness.

2. 2. The processing method according to claim 1, wherein in the annular groove forming step, the wafer is cut with a cutting blade having a first surface and a second surface behind the first surface, the diameter of the second surface side being set to a value larger than the diameter of the first surface side, and the tip cross section of the cutting blade being V-shaped.

3. The processing method according to claim 1 , wherein in the annular groove forming step, cutting is performed with a cutting blade at different positions in a width direction of the annular groove with different cutting depths.

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