JP2019186291A - Wafer processing method - Google Patents

Abstract

An object of the present invention is to suppress contamination attached to a device. Kind Code: A1 A wafer processing method includes a protective tape attaching step ST1 for attaching a protective tape to a surface of a wafer, and a grinding step ST2 for holding the protective tape and grinding the back surface of the wafer to reduce the thickness to a finished thickness. And a cutting groove forming step of holding a protective tape, cutting a cutting blade from the back surface of the wafer, and forming a cutting groove on the front surface side of the wafer with a remaining portion thinner than the finished thickness of the wafer along the planned dividing line. ST3, a sticking step of attaching a dicing tape to the back surface of the wafer having the cut grooves, fixing an outer peripheral edge of the dicing tape to an annular frame, and peeling the protective tape from the surface of the wafer; Cut the cutting blade to a depth that does not cut into the dicing tape along the dividing line from And a division step ST5 of dividing vice chip. [Selection] Figure 2

Description

  The present invention relates to a wafer processing method.

  2. Description of the Related Art A processing technique is widely used in which a wafer on which a device such as a semiconductor is formed is thinned to a finished thickness, and then cut by a cutting blade and divided into individual device chips. The wafer is usually cut in a state where the wafer is fixed to the annular frame with a dicing tape so that the wafer can be easily handled after being divided by cutting (see, for example, Patent Document 1 and Patent Document 2).

JP 2010-245446 A Japanese Patent No. 4880244

  However, in the conventional wafer processing method, the cutting blade is cut and divided up to the dicing tape, so that the adhesive layer of the adhesive tape adheres to the device together with the cutting waste (referred to as contamination) and affects the operation of the device. End up. For this reason, attempts have been made to change the processing method and the nozzle for injecting the cutting fluid supplied to the processing point so as to suppress the adhesion of contamination. However, in the conventional wafer processing method, it is difficult to completely suppress the adhesion of contamination.

  The present invention has been made in view of such problems, and an object thereof is to provide a wafer processing method capable of suppressing contamination adhering to a device.

  In order to solve the above-described problems and achieve the object, a wafer processing method according to the present invention is a wafer processing method for processing a wafer having a surface on which devices are formed in a plurality of regions partitioned by a plurality of division lines. A processing method comprising: a protective tape attaching step for attaching a protective tape to a front surface of a wafer; and holding the protective tape attached to the front surface of the wafer with a chuck table, and grinding the back surface of the wafer. A grinding step for thinning to a finished thickness, and after performing the protective tape attaching step and before or after performing the grinding step, hold the protective tape on the chuck table and cut the cutting blade from the back surface of the wafer. Forming a cutting groove that leaves a remaining portion thinner than the finished thickness of the wafer on the surface side of the wafer along the planned dividing line A dicing tape is attached to the back surface of the wafer on which the cutting groove is formed, and a frame unit is formed by fixing an outer peripheral edge of the dicing tape to an annular frame. A separation step to be peeled off, and a cutting blade is cut from the surface of the wafer subjected to the substitution step to a depth not to be cut into the dicing tape along the division line, and the remaining portion is cut. And dividing the wafer into individual device chips.

  In the wafer processing method, the protective tape may have the same diameter as the wafer.

  In the wafer processing method, the depth of the cutting groove formed in the cutting groove forming step or the cutting groove remaining after the grinding step may be ½ or less of the finished thickness of the wafer.

  The wafer processing method of the present invention produces an effect that contamination attached to the device can be suppressed.

FIG. 1 is a perspective view illustrating an example of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a flowchart showing a flow of a wafer processing method according to the first embodiment. FIG. 3 is a perspective view showing a protective tape attaching step of the wafer processing method shown in FIG. FIG. 4 is a side view showing a grinding step of the wafer processing method shown in FIG. FIG. 5 is a cross-sectional view showing a cutting groove step in the wafer processing method shown in FIG. FIG. 6 is a perspective view showing a state in which a dicing tape is attached to the back surface of the wafer in the attaching step of the wafer processing method shown in FIG. FIG. 7 is a perspective view showing a wafer from which the protective tape is peeled after FIG. FIG. 8 is a cross-sectional view showing a state after the dividing step of the wafer processing method shown in FIG. FIG. 9 is an enlarged cross-sectional view of a portion IX in FIG.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment 1
A wafer processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view illustrating an example of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a flowchart showing a flow of a wafer processing method according to the first embodiment.

  The wafer processing method according to the first embodiment is a method of processing the wafer 1 shown in FIG. In the first embodiment, the wafer 1 is a disk-shaped semiconductor wafer or optical device wafer having a substrate 2 made of silicon, sapphire, gallium or the like. As shown in FIG. 1, the wafer 1 includes a surface 3 on which devices 5 are formed in a plurality of regions partitioned by a plurality of division lines 4.

  The wafer processing method according to the first embodiment is a processing method for processing the wafer 1 shown in FIG. 1 and is a method for dividing the wafer 1 into individual device chips 6. The device chip 6 includes the device 5 and the substrate 2. As shown in FIG. 2, the wafer processing method includes a protective tape attaching step ST1, a grinding step ST2, a cutting groove forming step ST3, an attaching step ST4, and a dividing step ST5.

(Protective tape application step)
FIG. 3 is a perspective view showing a protective tape attaching step of the wafer processing method shown in FIG. The protective tape attaching step ST <b> 1 is a step for attaching the protective tape 10 to the surface 3 of the wafer 1. In Embodiment 1, as shown in FIG. 3, the protective tape sticking step ST1 sticks the protective tape 10 having the same diameter as the diameter 7 (shown in FIG. 1) of the wafer 1 on the surface 3 side. In the first embodiment, the protective tape 10 includes a base material layer 11 made of a synthetic resin and an adhesive layer 12 laminated on the base material layer 11 and adhered to the surface 3 of the wafer 1. In the wafer processing method, when the protective tape 10 is attached to the surface 3 of the wafer 1, the process proceeds to the grinding step ST2.

(Grinding step)
FIG. 4 is a side view showing a grinding step of the wafer processing method shown in FIG. Grinding step ST2 is a step in which the protective tape 10 attached to the front surface 3 of the wafer 1 is held by the chuck table 21 of the grinding device 20 and the back surface 9 of the wafer 1 is ground to a final thickness of 8. . In the grinding step ST <b> 2, the grinding device 20 holds the surface 3 side of the wafer 1 on the holding surface 22 of the chuck table 21 via the protective tape 10. In the first embodiment, the finished thickness 8 is 50 μm or more and 500 μm or less.

  In the grinding step ST2, as shown in FIG. 4, the grinding device 20 supplies grinding water while rotating the grinding wheel 24 around the axis by the spindle 23 and rotating the chuck table 21 around the axis. In the grinding step ST2, the grinding device 20 grinds the back surface 9 of the wafer 1 by bringing the grinding wheel 25 close to the chuck table 21 at a predetermined feed rate. The wafer processing method proceeds to the cutting groove forming step ST3 after the grinding step ST2.

(Cutting groove forming step)
FIG. 5 is a cross-sectional view showing a cutting groove step of the wafer processing method shown in FIG. In the cutting groove forming step ST3, the protective tape 10 is held by the chuck table 31 of the cutting device 30 and the cutting blade 35 from the back surface 9 of the wafer 1 after performing the grinding step ST2 after performing the protective tape attaching step ST1. And a cutting groove 101 is formed along the planned dividing line 4 leaving a remaining portion 100 thinner than the finished thickness 8 of the wafer 1 on the surface 3 side of the wafer 1. In the cutting groove forming step ST3, the cutting device 30 first sucks and holds the protective tape 10 side attached to the front surface 3 side of the wafer 1 on the holding surface 32 of the chuck table 31.

  In the cutting groove forming step ST3, the cutting device 30 images the back surface 9 of the wafer 1 with an infrared camera, and performs alignment for aligning the division line 4 and the cutting blade 35. In the cutting groove forming step ST3, the cutting device 30 supplies the cutting water 35 from the cutting water nozzle 33 to the wafer 1 held on the chuck table 31 while the cutting blade 35 mounted on the cutting unit 34 is moved to the back surface 9 side of the wafer 1. Is cut into the planned dividing lines 4 for a depth of 102 minutes that does not reach the front surface 3, and the cutting grooves 101 are formed on the respective planned dividing lines 4 of the wafer 1 from the back surface 9 side. In the first embodiment, the depth 102 of the cutting groove 101 formed in the cutting groove forming step ST3 is ½ of the finished thickness 8 of the wafer 1, but in the present invention, it is 20 μm or more and 1 of the finished thickness 8. / 2 or less is sufficient. In the wafer processing method, when the cutting grooves 101 are formed in all the division planned lines 4 of the wafer 1, the process proceeds to the attaching step ST4.

(Replacement step)
FIG. 6 is a perspective view showing a state in which a dicing tape is attached to the back surface of the wafer in the attaching step of the wafer processing method shown in FIG. FIG. 7 is a perspective view showing a wafer from which the protective tape is peeled after FIG.

  In the attaching step ST4, the dicing tape 13 is attached to the back surface 9 of the wafer 1 in which the cutting grooves 101 are formed, and the outer peripheral edge of the dicing tape 13 is fixed to the annular frame 14 to form the frame unit 15. In this step, the protective tape 10 is peeled off from the surface 3. In the replacement step ST4, as shown in FIG. 6, the wafer 1 is positioned in the opening 16 of the annular frame 14, and a dicing tape 13 having a diameter larger than the diameter 7 of the wafer 1 is attached to the back surface 9 of the wafer 1. At the same time, the outer peripheral edge of the dicing tape 13 is fixed to the annular frame 14 to form the frame unit 15 shown in FIG. The frame unit 15 is a unit that supports the wafer 1 in the opening 16 of the annular frame 14. The dicing tape 13 includes a base material layer 17 made of a synthetic resin and an adhesive layer 18 laminated on the base material layer 17 and attached to the back surface 9 and the annular frame 14 of the wafer 1.

  In the replacement step ST4, the protective tape 10 is peeled off from the surface 3 of the wafer 1 as shown in FIG. The wafer processing method proceeds to the dividing step ST5 after the attaching step ST4.

(Division step)
FIG. 8 is a cross-sectional view showing a state after the dividing step of the wafer processing method shown in FIG. FIG. 9 is an enlarged cross-sectional view of a portion IX in FIG. In the dividing step ST5, the cutting blade 46 of the cutting device 40 is cut from the surface 3 of the wafer 1 on which the re-sticking step ST4 has been performed to a depth that does not cut into the dicing tape 13 along the dividing line 4, and the remaining portion In this step, 100 is cut to divide the wafer 1 into individual device chips 6. In the division step ST5, the cutting device 40 first sucks and holds the dicing tape 13 side attached to the back surface 9 side of the wafer 1 on the holding surface 42 of the chuck table 41, and clamps the annular frame 14 with the clamp portion 43. To do.

  In the division step ST5, the cutting device 40 images the surface 3 of the wafer 1 with the imaging unit, and performs alignment for aligning the division line 4 and the cutting blade 46. In the division step ST5, the cutting device 40 supplies the cutting water to the wafer 1 held on the chuck table 41 from the cutting water nozzle 44, and the cutting blade mounted on the cutting unit 45 as shown in FIGS. The wafer 1 is divided into the individual device chips 6 by cutting into the dividing line 4 by a depth that reaches the groove bottom of the cutting groove 101 from the surface 3 side of the wafer 1 and does not reach the dicing tape 13. . The wafer processing method ends when the wafer 1 is divided into individual device chips 6.

  In the wafer processing method according to the first embodiment, after forming the cutting groove 101 from the back surface 9, the groove bottom of the cutting groove 101 is cut from the front surface 3 and divided into individual device chips 6. The dicing tape 13 is not cut. As a result, the wafer processing method can suppress the adhesion layers 12 and 18 from adhering to the device chip 6 and can suppress contamination from adhering to the device 5. Further, the wafer processing method utilizes the fact that the wafer 1 is always ground, and uses the protective tape 10 (tape for protecting the surface 3 on which the device 5 of the wafer 1 is formed) used for grinding on the back surface 9 side. Since the cutting groove 101 is formed, the waste of the tape such as the protective tape 10 can be suppressed.

  Next, the present inventor confirmed the effect of the wafer processing method of the above-described embodiment. The results are shown in Table 1.

  In Table 1, when the finished thickness 8 of the wafer 1 is 60 μm, the depth 102 of the cutting groove 101 is 5 μm, the comparative example 1 is used, and the depth 102 of the cutting groove 101 is 20 μm. In the present invention, the depth 102 of the cutting groove 101 is ½ of the finished thickness 8 is referred to as Product 2 of the present invention, and the depth 102 of the cutting groove 101 is 40 μm as Comparative Example 2. In Table 1, the adhesion state of the contamination to the device 5 after the division into the device chips 6 of Comparative Examples 1 and 2 and Invention Products 1 and 2 was confirmed, and there was no contamination adhesion, almost no contamination, and during the processing process The wafer 1 is indicated by a circle with no damage, and the wafer 1 is indicated by a cross when there is contamination or the wafer 1 is damaged during the processing step.

  According to Table 1, Comparative Example 1 and Comparative Example 2 have contamination adherence, while the inventive product 1 and the inventive product 2 have no or almost no contamination, and the wafer is in the process. 1 was not damaged. Therefore, according to Table 1, it became clear that the adhesion of contamination to the device 5 can be suppressed by setting the depth 102 of the cutting groove 101 to 20 μm or more and 1/2 or less of the finished thickness 8.

  The present invention is not limited to the first embodiment. That is, various modifications can be made without departing from the scope of the present invention. In the first embodiment, the cutting groove forming step ST3 is performed after performing the grinding step ST2 after performing the protective tape adhering step ST1, but the present invention performs grinding after performing the protective tape adhering step ST1. Prior to performing step ST2, a cutting groove forming step ST3 may be performed. In this case, the depth of the cutting groove 101 formed in the cutting groove forming step ST3 is set such that the depth 102-1 of the cutting groove 101 remaining after the grinding step ST2 is 20 μm or more and 1/2 or less of the finished thickness 8 of the wafer 1. It forms so that it becomes.

1 Wafer 3 Surface 4 Divided Line 5 Device 6 Device Chip 7 Diameter 8 Finished Thickness 10 Protective Tape 13 Dicing Tape 14 Annular Frame 15 Frame Unit 21 Chuck Table 31 Chuck Table 35 Cutting Blade 100 Remaining Portion 101 Cutting Groove 102 Depth ST1 Protection tape sticking step ST2 Grinding step ST3 Cutting groove forming step ST4 Pasting step ST5 Dividing step

Claims (3)

A wafer processing method for processing a wafer having a surface on which a device is formed in a plurality of regions partitioned by a plurality of division lines,
A protective tape attaching step for attaching a protective tape to the surface of the wafer;
Grinding step of holding the protective tape attached to the front surface of the wafer with a chuck table and grinding the back surface of the wafer to a final thickness;
After carrying out the protective tape attaching step and before or after carrying out the grinding step, the protective tape is held by a chuck table and a cutting blade is cut from the back surface of the wafer, and the front surface side of the wafer is A cutting groove forming step for forming a cutting groove that leaves a remaining portion thinner than the finished thickness of the wafer along the planned dividing line;
A dicing tape is affixed to the back surface of the wafer in which the cutting grooves are formed, and a frame unit is formed by fixing the outer peripheral edge of the dicing tape to an annular frame, and the protective tape is peeled off from the front surface of the wafer. A replacement step;
A cutting blade is cut from the surface of the wafer subjected to the reattachment step to a depth that does not cut into the dicing tape along the division line, and the remaining portion is cut to separate the wafer into individual device chips. A wafer processing method comprising: a dividing step for dividing the wafer into two.   The wafer processing method according to claim 1, wherein the protective tape has the same diameter as the wafer.   3. The wafer processing method according to claim 1, wherein a depth of the cutting groove formed in the cutting groove forming step or a cutting groove remaining after the grinding step is ½ or less of a finished thickness of the wafer.

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