JP2020188101A - Method for manufacturing circular substrate - Google Patents

Abstract

To provide a method for manufacturing a circular substrate capable of appropriately discharging heat generated when the substrate is punched out by a core drill.SOLUTION: A method for manufacturing a circular substrate smaller than a substrate having one side surface and the other side surface, from the substrate, includes: a tape sticking step for sticking a tape on the other side surface of the substrate; a holding step for holding the substrate with a holding table via the tape; a blanking step for blanking the substrate with a core drill to form the circular substrate by rotating the core drill having a diameter smaller than the substrate to make the core drill cut from one side surface of the substrate to the other side surface while supplying a machining liquid to the core drill; and a detaching step for detaching the circular substrate from the tape to remove the same. In the blanking step, movement of the core drill in a direction approaching the tape and movement in a direction away from the tape are repeated while the core drill is made to cut from one side surface of the substrate to the other side surface.SELECTED DRAWING: Figure 7

Description

The present invention relates to a method for manufacturing a circular substrate.

For the production of device chips to be incorporated in various electronic devices, for example, circular (disk-shaped) wafers made of semiconductor materials such as silicon are used. For this wafer, a cylindrical ingot is sliced with a wire saw or the like to form a circular asslice wafer, the flatness of the front and back surfaces thereof is improved by a wrapping process, and then the corners remaining on the outer peripheral portion are chamfered. Obtained at.

By the way, if there is a problem with the quality of the wafer, a device chip having insufficient performance is likely to be produced. In such a case, for example, the target wafer is discarded. On the other hand, if the entire wafer is discarded even though there is a problem only in the quality of a part of the wafer, it is uneconomical because most of the wafers having no problem in quality are also discarded.

Therefore, when there is a problem only in the quality of a part of the wafer, the wafer may be hollowed out in a circular shape to form a wafer having a small diameter that does not include the part having a problem in the quality. Further, when a wafer having a large diameter cannot be used due to equipment used for producing device chips or the like, this wafer may be hollowed out in a circular shape to form a wafer having a small diameter.

When a circular member (hereinafter, circular substrate) is hollowed out from a plate-shaped member (hereinafter, substrate) such as a wafer, for example, a cutting blade (for example, a patent document) formed by fixing a plurality of abrasive grains with a binder. 1) and tools such as core drills are used. Since the core drill is formed in a cylindrical shape suitable for hollowing out a substrate, the substrate can be hollowed out in a shorter time than a cutting blade to form a circular substrate.

Japanese Unexamined Patent Publication No. 11-54461

When the substrate is hollowed out with the core drill, a processing liquid such as water is supplied to the processing point where the core drill and the substrate come into contact with each other, as in the case of processing the substrate with a cutting blade. However, due to the structure of the core drill, it is difficult to supply a large amount of machining fluid to the machining point, so it is difficult for the heat generated at the machining point to be discharged, and problems such as deterioration of machining accuracy and abnormal wear of the core drill due to this heat become problems. Was there.

The present invention has been made in view of such problems, and an object of the present invention is to provide a method for manufacturing a circular substrate capable of appropriately discharging heat generated when a substrate is hollowed out by a core drill.

According to one aspect of the present invention, there is a method for manufacturing a circular substrate, which is a method for manufacturing a circular substrate smaller than the substrate from a substrate having one surface and the other surface on the opposite side of the one surface. A tape sticking step of sticking a tape to the other surface of the substrate, a holding step of holding the substrate on a holding table via the tape after performing the tape sticking step, and the holding step. After this, the substrate is cut by rotating a core drill having a diameter smaller than that of the substrate and cutting the core drill from one surface of the substrate to the other surface while supplying the processing liquid to the core drill. A hollowing step for forming the circular substrate by hollowing out with the core drill and a removing step for peeling and removing the circular substrate from the tape after performing the hollowing out step are provided. While cutting from one surface of the substrate to the other surface, the core drill repeatedly moves the core drill toward the tape and away from the tape, and the core drill cuts the substrate. Provided is a method for manufacturing a circular substrate in which the processing liquid is impregnated into a processing point to be processed.

In one aspect of the present invention, it is preferable to further include a mark forming step for forming a mark indicating the direction of the circular substrate before carrying out the removing step.

In the method for manufacturing a circular substrate according to one aspect of the present invention, when the substrate is hollowed out with a core drill to form a circular substrate, the movement of the core drill in the direction approaching the tape and the movement in the direction away from the tape are repeated. Since the core drill infiltrates the machining fluid into the machining point where the substrate is machined, a sufficient amount of machining fluid can be supplied to the machining point. As a result, this processing liquid can appropriately discharge the heat generated when the substrate is hollowed out by the core drill.

Further, in the method for manufacturing a circular substrate according to one aspect of the present invention, a tape is attached to the other surface of the substrate, and then a core drill is cut from one surface to the other surface of the substrate to cut the substrate. Since the circular substrate is formed by hollowing out with a core drill, the circular substrate is in a state of being connected to the substrate via tape. Therefore, the circular substrate does not fit into the core drill and cannot be taken out.

It is a perspective view which shows the structural example of a substrate schematically. It is a perspective view which shows typically the state which the tape is attached to the substrate. It is a partial cross-sectional side view which shows typically the state which the substrate is held by the holding table. It is a perspective view which shows typically how the mark which shows a direction is formed on a substrate. It is a top view which shows typically the substrate on which the mark was formed. It is a perspective view which shows typically how the substrate is hollowed out by a core drill. 7 (A), 7 (B), 7 (C), and 7 (D) are cross-sectional views schematically showing how the core drill moves. It is a perspective view which shows typically how the circular substrate is removed from a tape. It is a perspective view which shows typically how the mark which shows a direction is formed on a substrate in a modification.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a configuration example of a substrate 11 used in the method for manufacturing a circular substrate according to the present embodiment. The substrate 11 used in the present embodiment is, for example, a circular (disk-shaped) wafer made of crystalline silicon (Si), and has a substantially flat first surface (one surface) 11a and the first surface. It has a second surface (the other surface) 11b opposite to 11a.

A notch 11c indicating the crystal orientation is provided on the outer peripheral edge of the substrate 11. However, an orientation flat or the like may be provided instead of the notch 11c. The diameter (= D1) of the substrate 11 is larger than the diameter of the circular substrate manufactured in this embodiment. The thickness (= T1) of the substrate 11 is equal to or greater than the thickness of the circular substrate manufactured in this embodiment.

In the present embodiment, a circular (disk-shaped) wafer made of crystalline silicon is used as the substrate 11, but the material, shape, structure, size, etc. of the substrate 11 are not limited. For example, a substrate 11 having an arbitrary shape made of other materials such as semiconductors, ceramics, resins, and metals can be used.

In the method for manufacturing a circular substrate according to the present embodiment, first, a tape is attached (attached) to the second surface 11b of the substrate 11 described above (tape attachment step). FIG. 2 is a perspective view schematically showing a state in which the tape 13 is attached to the substrate 11. In the present embodiment, for example, a tape 13 having a diameter larger than that of the substrate 11 is attached to the second surface 11b side of the substrate 11.

The tape 13 typically includes a film-like base material and a glue layer provided on the surface of the base material. The tape 13 is attached to the substrate 11 by bringing the glue layer of the tape 13 into close contact with the second surface 11b of the substrate 11. Further, the outer peripheral portion of the tape 13 is fixed to the annular frame 15 surrounding the substrate 11. As a result, the substrate 11 is in a state of being supported by the frame 15 via the tape 13.

However, there are no restrictions on the material, shape, structure, size, etc. of the tape 13. The tape 13 may be any tape 13 as long as it can connect the circular substrate formed by hollowing out the substrate 11 and the substrate 11. Therefore, the tape 13 smaller than the substrate 11 can be attached to the second surface 11b of the substrate 11. If the tape 13 is smaller than the substrate 11, the frame 15 is not fixed to the tape 13. In this way, the frame 15 does not necessarily have to be fixed to the tape 13.

After the tape 13 is attached to the second surface 11b of the substrate 11, the substrate 11 is held by the holding table (chuck table) via the tape 13 (holding step). FIG. 3 is a partial cross-sectional side view schematically showing a state in which the substrate 11 is held by the holding table (chuck table) 2. The holding table 2 includes, for example, a cylindrical frame 4 made of a metal material typified by stainless steel, and a holding plate 6 made of a porous material and arranged on the upper part of the frame 4.

The upper surface of the holding plate 6 is a holding surface 6a that holds the substrate 11 via the tape 13. The lower surface side of the holding plate 6 is connected to a suction source (not shown) via a flow path 4a or the like provided inside the frame body 4. A valve (not shown) for controlling the flow of fluid is provided in the flow path 4a or the like. Therefore, if the valve is opened, the negative pressure of the suction source can be applied to the holding surface 6a.

A plurality of clamps 8 used for fixing the frame 15 are provided around the frame body 4. The frame body 4 (holding table 2) is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially perpendicular to the above-mentioned holding surface 6a. Further, the frame body 4 (holding table 2) is supported by a moving mechanism (not shown), and moves in a direction (horizontal direction) substantially parallel to the holding surface 6a described above.

When holding the substrate 11 on the holding table 2, first, the base material side of the tape 13 attached to the substrate 11 is brought into contact with the holding surface 6a of the holding table 2. Then, the valve is opened to apply the negative pressure of the suction source to the holding surface 6a. As a result, the tape 13 is attracted to the holding surface 6a, and the substrate 11 is held on the holding table 2 with the first surface 11a side exposed upward. Further, the frame 15 is fixed by the clamp 8.

After the substrate 11 is held by the holding table 2, a mark is formed on the substrate 11 (mark forming step). FIG. 4 is a perspective view schematically showing how the mark 11d is formed on the substrate 11, and FIG. 5 is a plan view schematically showing the substrate 11 on which the mark 11d is formed. In the present embodiment, the mark 11d indicating the crystal orientation (direction) is formed on the substrate 11. That is, the mark 11d having the information corresponding to the notch 11c is formed on the substrate 11.

The mark 11d is also formed in the inner region of the circular scheduled machining line 11e into which the core drill is cut later. That is, the mark 11d is also formed in the region of the circular substrate. With such a mark 11d, the crystal orientation of the circular substrate can be easily confirmed even after being separated from the substrate 11.

However, another mark 11d indicating the direction of the circular substrate may be formed on the substrate 11. That is, the direction indicated by the mark 11d does not have to be the crystal orientation. The method of forming the mark 11d is not particularly limited, but in the present embodiment, a method of cutting the first surface 11a of the substrate 11 is used. As shown in FIG. 4, the cutting unit 12 is arranged above the substrate 11 held by the holding table 2.

The cutting unit 12 includes, for example, a tubular spindle housing 14. In the space inside the spindle housing 14, a spindle 16 which is a rotation axis substantially parallel to the holding surface 6a of the holding table 2 is housed. An annular cutting blade 18 formed by fixing abrasive grains with a binder is mounted on one end side of the spindle 16.

A rotary drive source (not shown) such as a motor is connected to the other end side of the spindle 16, and the cutting blade 18 mounted on one end side of the spindle 16 rotates by the force generated by the rotary drive source. The cutting unit 12 (spindle housing 14) is supported by, for example, a moving mechanism (not shown), and is substantially perpendicular to the holding surface 6a (vertical direction) and substantially parallel to the holding surface 6a. Move in the direction (horizontal direction).

When forming the mark 11d on the substrate 11, for example, the cutting blade 18 is rotated so that the lower end of the cutting blade 18 is lower than the first surface 11a of the substrate 11, so that the cutting unit 12 with respect to the holding table 2 is formed. Adjust the height. Then, the holding table 2 and the cutting unit 12 are moved relatively in a direction substantially parallel to the holding surface 6a so that the cutting blade 18 moves along the formed region of the mark 11d.

As a result, as shown in FIG. 4, the cutting blade 18 can be cut into the first surface 11a of the substrate 11 along the formed region of the mark 11d to form the mark 11d indicating the crystal orientation. Since the mark 11d has information corresponding to the notch 11c of the substrate 11, the crystal orientation of the circular substrate cut out from the substrate 11 can be confirmed based on the mark 11d. As shown in FIG. 5, in the present embodiment, the mark 11d is formed in all the regions of the circular substrate.

After the mark 11d is formed on the substrate 11, the substrate 11 is hollowed out with a core drill having a diameter smaller than that of the substrate 11 to form a circular substrate (hollowing step). FIG. 6 is a perspective view schematically showing how the substrate 11 is hollowed out by the core drill 22. The core drill 22 includes, for example, a spindle 24 that is a rotation axis that is substantially perpendicular to the holding surface 6a.

A bit 26 is mounted on one end side of the spindle 24. The bit 26 includes a cylindrical hollow body 28 made of metal or the like, and a cutting blade 30 provided on the annular lower surface of the hollow body 28. The cutting blade 30 is, for example, a grindstone in which abrasive grains are fixed with a binder. The diameter of the hollow body 28 corresponds to the diameter (= D2) of the circular processing schedule line 11e, and is smaller than the diameter of the substrate 11 (= D1).

A rotation drive source (not shown) such as a motor is connected to the other end side of the spindle 24, and the bit 26 mounted on one end side of the spindle 24 rotates by the force generated by the rotation drive source. The spindle 24 of the core drill 22 is supported by, for example, a moving mechanism (not shown), and has a direction substantially perpendicular to the holding surface 6a (vertical direction) and a direction substantially parallel to the holding surface 6a (horizontal direction). Direction) and move to. A nozzle 42 is arranged on the side of the core drill 22.

When the substrate 11 is hollowed out by the core drill 22, the position of the core drill 22 is adjusted with respect to the holding table 2 that holds the substrate 11 so that the cutting blade 30 is arranged directly above the circular machining schedule line 11e. Then, the bit 26 is rotated to move the core drill 22 in the direction (downward) approaching the holding table 2 while supplying the machining fluid 44 such as pure water from the nozzle 42 to the cutting blade 30.

As a result, as shown in FIG. 6, the cutting blade 30 is cut into the substrate 11 along the circular machining schedule line 11e, and the substrate 11 can be hollowed out in a circular shape. That is, in the present embodiment, the core drill 22 (cutting blade 30) is cut from the first surface 11a to the second surface 11b of the substrate 11 to cut the substrate 11 along the scheduled machining line 11e. However, it is necessary to adjust the height of the core drill 22 with respect to the holding table 2 so that the tape 13 is not cut by the core drill 22.

By the way, due to the structure of the core drill 22 as described above, a large amount of processing liquid 44 is supplied to the processing point where the core drill 22 processes the substrate 11 (that is, the contact point where the cutting blade 30 and the substrate 11 come into contact with each other). Is difficult. Therefore, the heat generated at the machining point is not properly discharged, and the deterioration of machining accuracy and abnormal wear of the cutting blade 30 due to this heat are likely to cause problems.

Therefore, in the method for manufacturing a circular substrate according to the present embodiment, the holding table 2 of the core drill 22 is used until the core drill 22 (cutting blade 30) is cut from the first surface 11a to the second surface 11b of the substrate 11. The movement in the direction approaching (downward) and the movement in the direction away from the holding table 2 (upward) are repeated. That is, the movement of the core drill 22 in the direction approaching the tape 13 and the movement in the direction away from the tape 13 are repeated.

7 (A), 7 (B), 7 (C), and 7 (D) are cross-sectional views schematically showing how the core drill 22 (cutting blade 30) moves. As shown in FIG. 7A, when the core drill 22 moves downward and the cutting blade 30 comes into contact with the first surface 11a side of the substrate 11, a part of the substrate 11 is scraped off and the first surface 11a side. A groove (processing mark) 11f is formed in the groove.

The conditions for moving the core drill 22 downward (for example, the speed of movement) are adjusted within a range in which the influence of heat generated at the machining point does not matter. For example, when the rotation speed of the core drill 22 is 3000 rpm to 5000 rpm (typically 4000 rpm), the moving speed is 3 μm / sec to 7 μm / sec (typically 5 μm / sec), and the moving time is set. Is set to 3 to 7 seconds (typically 4 seconds) from the time when the cutting blade 30 and the substrate 11 come into contact with each other.

After moving the core drill 22 downward, the core drill 22 is moved upward as shown in FIG. 7 (B). As a result, the machining fluid 44 supplied from the nozzle 42 flows into the groove 11f. The conditions for moving the core drill 22 upward (for example, the speed of movement) are adjusted within a range in which an appropriate amount of the working liquid 44 is supplied to the inside of the groove 11f. For example, the cutting blade 30 is moved upward to a height that does not contact the first surface 11a of the substrate 11 at a speed of 10 μm / sec to 30 μm / sec (typically 20 μm / sec), which is larger than the downward moving speed. ..

If the time for moving the core drill 22 upward is too long with respect to the time for moving the core drill 22 downward, the productivity of the circular substrate decreases. Further, if the time for moving the core drill 22 downward is too long, the influence of heat generated at the machining point tends to become a problem. Therefore, the time t1 for moving the core drill 22 downward and the time t2 for moving the core drill 22 upward are, for example, a range satisfying 1 ≦ t1 / t2 ≦ 15, preferably 2 ≦ t1 / t2 ≦ 10. It is adjusted with. However, the conditions for moving the core drill 22 do not necessarily satisfy these conditions.

After moving the core drill 22 upward, the core drill 22 is moved downward again as shown in FIG. 7 (C). As a result, a part of the substrate 11 is further scraped off, and the groove 11f on the first surface 11a side becomes deeper. The conditions for the downward movement of the core drill 22 may be the same as or different from the conditions for the downward movement according to FIG. 7 (A).

As described above, by moving the core drill 22 upward, an appropriate amount of the machining fluid 44 is invaded into the machining point (inside the groove 11f). Therefore, even when the substrate 11 is processed again by the subsequent downward movement, the heat generated at the processing point is easily discharged appropriately. After moving the core drill 22 downward, the core drill 22 is moved upward again as shown in FIG. 7 (D). By repeating the downward movement and the upward movement of the core drill 22 in this way, the problem caused by the heat generated at the machining point can be solved.

After the substrate 11 is hollowed out with the core drill 22 along the arbitrary scheduled machining line 11e to form the circular substrate 17 (see FIG. 8), the core drill 22 is used along all the other scheduled machining lines 11e in the same procedure. The substrate 11 is hollowed out to form a circular substrate 17. A tape 13 is attached to the second surface 11b of the substrate 11.

Further, the tape 13 is not cut by the core drill 22. Therefore, the circular substrate 17 formed by hollowing out the substrate 11 with the core drill 22 is in a state of being connected to the remaining portion of the substrate 11 via the tape 13. Therefore, even if the core drill 22 is moved upward after the substrate 11 is hollowed out by the core drill 22, the circular substrate 17 stays at the same height as the remaining portion of the substrate 11. That is, the circular substrate 17 does not fit into the bit 26 of the core drill 22 and cannot be taken out.

After the substrate 11 is hollowed out with the core drill 22 along all the scheduled processing lines 11e to form the circular substrate 17, the circular substrate 17 is peeled off from the tape 13 and removed (removal step). FIG. 8 is a perspective view schematically showing how the circular substrate 17 is removed from the tape 13.

For example, when the glue layer of the tape 13 contains a curable resin that is cured by light, the tape 13 is irradiated with light to reduce the adhesive force of the glue layer, whereby the tape 13 to the circular substrate 17 are formed. Can be easily peeled off and removed. There are no particular restrictions on the specific method for peeling and removing the circular substrate 17 from the tape 13.

As shown in FIG. 8, the circular substrate 17 removed from the tape 13 has a first surface (one surface) 17a corresponding to the first surface 11a of the substrate 11 and a second surface 11b corresponding to the second surface 11b of the substrate 11. It has two surfaces (the other surface) 17b. The diameter (= D2) of the circular substrate 17 is equal to the diameter (= D2) of the circular machining schedule line 11e set on the substrate 11. Further, a part of the mark 11d becomes a mark 17c indicating the crystal orientation (direction) of the circular substrate 17.

As described above, in the method for manufacturing a circular substrate according to the present embodiment, when the substrate 11 is hollowed out by the core drill 22 to form the circular substrate 17, the direction is such that the substrate 11 approaches the holding table 2 (tape 13) of the core drill 22. Since the core drill 22 infiltrates the machining liquid 44 into the machining point where the substrate 11 is machined by repeating the movement and the movement in the direction away from the holding table 2, a sufficient amount of the machining fluid 44 can be supplied to the machining point. As a result, the processing liquid 44 can appropriately discharge the heat generated when the substrate 11 is hollowed out by the core drill 22.

Further, in the method for manufacturing a circular substrate according to the present embodiment, the tape 13 is attached to the second surface (the other surface) 11b of the substrate 11 and then from the first surface (one surface) 11a of the substrate 11. By cutting the core drill 22 up to the second surface 11b, the substrate 11 is hollowed out by the core drill 22 to form the circular substrate 17, so that the circular substrate 17 is connected to the substrate 11 via the tape 13. Therefore, the circular substrate 17 does not fit into the core drill 22 and cannot be taken out.

The present invention is not limited to the description of the above-described embodiment, and can be implemented with various modifications. For example, in the above-described embodiment, the mark 11d is formed on the substrate 11 and then the substrate 11 is hollowed out by the core drill 22, but the mark 11d is at least before the circular substrate 17 is peeled off from the tape 13 and removed. , It may be formed on the substrate 11. That is, the mark forming step can be performed at any timing before the removing step.

FIG. 9 is a perspective view schematically showing how the mark 11d indicating the direction is formed on the substrate 11 in the modified example. In this modification, the mark 11d is formed on the substrate 11 after the substrate 11 is hollowed out by the core drill 22. The details of the specific procedure are the same as those in the above-described embodiment.

Further, in the above-described embodiment, the mark 11d is formed by a method of cutting the first surface 11a of the substrate 11, but there is no particular limitation on the method of forming the mark 11d. For example, the mark 11d can be formed by irradiating the first surface 11a of the substrate 11 with a laser beam having a wavelength absorbed by the substrate 11 (wavelength having absorbency). Similarly, there are no particular restrictions on the shape of the mark 11d, the position where the mark 11d is formed, or the like.

In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be appropriately modified and implemented without departing from the scope of the object of the present invention.

11: Substrate 11a: First surface (one surface)
11b: Second surface (the other surface)
11c: Notch 11d: Mark 11e: Scheduled machining line 11f: Groove (machining mark)
13: Tape 15: Frame 17: Circular substrate 17a: First surface (one surface)
17b: Second surface (the other surface)
17c: Mark 2: Holding table (chuck table)
4: Frame body 4a: Flow path 6: Holding plate 6a: Holding surface 8: Clamp 12: Cutting unit 14: Spindle housing 16: Spindle 18: Cutting blade 22: Core drill 24: Spindle 26: Bit 28: Hollow body 30: Cutting Blade 42: Nozzle 44: Processing liquid

Claims (2)

A method for manufacturing a circular substrate, which manufactures a circular substrate smaller than the substrate from a substrate having one surface and the other surface on the opposite side of the one surface.
A tape sticking step of sticking the tape to the other side of the substrate,
After performing the tape sticking step, a holding step of holding the substrate on the holding table via the tape, and a holding step.
After performing the holding step, a core drill having a diameter smaller than that of the substrate is rotated to cut the core drill from one surface of the substrate to the other surface while supplying the processing liquid to the core drill. To form the circular substrate by hollowing out the substrate with the core drill.
After performing the hollowing out step, a removing step of peeling and removing the circular substrate from the tape is provided.
In the hollowing step, while the core drill is cut from one surface of the substrate to the other surface, the core drill moves toward the tape and moves away from the tape. A method for producing a circular substrate, which comprises repeatedly impregnating the processing liquid into a processing point where the core drill processes the substrate. The method for manufacturing a circular substrate according to claim 1, further comprising a mark forming step for forming a mark indicating the direction of the circular substrate before carrying out the removing step.