JP7285731B2 - Method for forming a circular substrate - Google Patents

Description

The present invention relates to a circular substrate forming method for forming a circular substrate smaller than the substrate from a substrate.

Wafers are usually formed by slicing an ingot. However, if the quality of the wafer in a predetermined area is poor or due to equipment reasons, a circular substrate is cut out from a substrate such as a wafer formed by slicing an ingot. (see, for example, Patent Document 1 and Patent Document 2). Cutting blades and core drills are used to hollow out circular substrates from substrates.

JP-A-11-64461 Japanese Patent Application Laid-Open No. 2015-50400

A core drill has the advantage of being able to hollow out a circular substrate from a substrate in a short period of time compared to machining with a cutting blade. However, when a core drill is used, it is difficult to supply the machining fluid to the machining point, and there are problems such as deterioration of machining quality due to machining heat and abnormal wear of the tool. Furthermore, there is also the problem that the circular substrate after hollowing out is caught in the core drill.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of forming a circular substrate that can suppress deterioration of processing quality.

In order to solve the above-described problems and achieve the object, the present invention provides a method for forming a circular substrate in which a circular substrate smaller than the substrate is formed from a substrate, and a circular substrate is formed on the back surface of the substrate. a tape applying step of applying a tape; a holding step of holding the substrate on a holding table through the tape; a bank wall placement step of placing a bank wall higher than the thickness of a substrate; a liquid supplying step of supplying a liquid to the inside of the bank wall after performing the bank wall placement step to submerge the substrate; After performing the supplying step, a cutting step of rotating a core drill having a diameter smaller than that of the substrate and cutting with the core drill from the surface of the substrate to the tape to form a circular substrate; and a removing step of removing the circular substrate from the tape after performing.

In the method for forming a circular substrate, the cutting step may be performed while supplying a cutting fluid to the core drill.

In the method for forming a circular substrate, in the cutting step, after cutting the surface of the substrate with the core drill, the tape may be repeatedly moved toward and away from the tape.

ADVANTAGE OF THE INVENTION This invention is effective in the ability to suppress deterioration of processing quality.

FIG. 1 is a perspective view showing an example of a substrate to be processed by a method for forming a circular substrate according to Embodiment 1. FIG. FIG. 2 is a perspective view showing an example of a circular substrate formed by the method for forming a circular substrate according to Embodiment 1. FIG. FIG. 3 is a flow chart showing the flow of the circular substrate forming method according to the first embodiment. 4 is a perspective view of the substrate after the taping step of the method of forming the circular substrate shown in FIG. 3; FIG. 5 is a perspective view schematically showing an identification mark forming step in the method of forming the circular substrate shown in FIG. 3. FIG. 6 is a plan view of the substrate after the identification mark forming step of the circular substrate forming method shown in FIG. 3. FIG. FIG. 7 is a perspective view showing the embankment placement step of the method of forming the circular substrate shown in FIG. 8 is a side view, partly in section, showing a holding step in the method of forming the circular substrate shown in FIG. 9 is a perspective view showing the essential part of the liquid supply step of the method of forming the circular substrate shown in FIG. 3. FIG. FIG. 10 is a side view showing, in partial cross section, the liquid supply step of the method for forming the circular substrate shown in FIG. 11 is a perspective view showing the main part of the cutting step of the method of forming the circular substrate shown in FIG. 3. FIG. 12 is a cross-sectional view showing the main part of the cutting step of the method of forming the circular substrate shown in FIG. 3. FIG. 13 is a perspective view showing a main part of a removing step in the method of forming the circular substrate shown in FIG. 3. FIG. 14 is a flow chart showing the flow of a method for forming a circular substrate according to a modification of Embodiment 1. FIG.

A form (embodiment) 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. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions, or changes in configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
A method for forming a circular substrate according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a substrate to be processed by a method for forming a circular substrate according to Embodiment 1. FIG. FIG. 2 is a perspective view showing an example of a circular substrate formed by the method for forming a circular substrate according to Embodiment 1. FIG. FIG. 3 is a flow chart showing the flow of the circular substrate forming method according to the first embodiment.

A method of forming a circular substrate according to the first embodiment is a method of forming a circular substrate 10 by cutting a circular substrate 10 shown in FIG. 2 having an outer diameter 11 smaller than that of the substrate 1 shown in FIG. is. The substrate 1 and the circular substrate 10 are wafers such as disk-shaped semiconductor wafers and optical device wafers made of silicon, sapphire, gallium arsenide, or the like. A device (not shown) is formed on the surface 12 of the base material of the circular substrate 10 . The device is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration).

In Embodiment 1, the substrate 1 is formed with the notch 3 indicating the crystal orientation as shown in FIG. 1, and the circular substrate 10 is formed with the orientation flat 13 indicating the crystal orientation as shown in FIG. ing. In addition, in the present invention, the substrate 1 may be formed with an orientation flat instead of the notch 3 .

As shown in FIG. 3, the method of forming a circular substrate according to the first embodiment includes a tape attaching step ST1, an identification mark forming step ST2, a bank wall arranging step ST3, a holding step ST4, and a liquid supplying step ST5. , a cutting step ST6 and a removing step ST7.

(Tape sticking step)
4 is a perspective view of the substrate after the taping step of the method of forming the circular substrate shown in FIG. 3; FIG. The tape attaching step ST1 is a step of attaching the tape 20 to the rear surface 4 of the front surface 2 of the substrate 1 .

In the first embodiment, in the tape attaching step ST1, a disk-shaped tape 20 having a diameter larger than that of the substrate 1 is attached to the rear surface 4 of the substrate 1, and an annular frame 21 is attached to the outer peripheral edge of the tape 20. , the substrate 1 is supported by an annular frame 21, as shown in FIG.

(Identification mark forming step)
5 is a perspective view schematically showing an identification mark forming step in the method of forming the circular substrate shown in FIG. 3. FIG. 6 is a plan view of the substrate after the identification mark forming step of the circular substrate forming method shown in FIG. 3. FIG. The identification mark forming step ST2 is a step of forming a half-cut groove 22 in the substrate 1, which becomes the orientation flat 13 of the circular substrate 10. FIG.

In Embodiment 1, in the identification mark forming step ST2, the cutting device 30 shown in FIG. In the first embodiment, in the identification mark forming step ST2, the cutting device 30, as shown in FIG. are relatively moved, the cutting blade 32 is cut to the center of the substrate 1 in the thickness direction.

In the first embodiment, in the identification mark forming step ST2, the cutting device 30 forms the half-cut grooves 22 concave from the surface of the substrate 1 between the outer edges of the substrate 1 . In Embodiment 1, the half-cut grooves 22 are formed at the end of the substrate 1 near the notch 3 and at the central portion of the substrate 1, as shown in FIG. The interval between the half-cut grooves 22 is slightly larger than the outer diameter 11 of the circular substrate 10 . In Embodiment 1, in the identification mark forming step ST2, the cutting device 30 forms the half-cut grooves 22 by cutting. The half-cut grooves 22 may be formed by ablation processing. Further, in the present invention, dividing grooves for dividing the substrate 1 may be formed by cutting or laser beam irradiation instead of the half-cut grooves 22, and chopper marks or the like may be formed.

(Dike wall placement step)
FIG. 7 is a perspective view showing the embankment placement step of the method of forming the circular substrate shown in FIG. In Embodiment 1, embankment placement step ST3 is a step of arranging embankment wall 23 on the outer peripheral side of substrate 1 and higher than thickness 5 of substrate 1 surrounding substrate 1 before carrying out holding step ST4. .

In Embodiment 1, in the embankment wall placement step ST3, a ring-shaped ring having an inner diameter larger than the outer diameter of the substrate 1, an outer diameter smaller than the inner diameter of the annular frame 21, and a thickness 24 thicker than the thickness 5 of the substrate 1 is formed. prepare the embankment wall 23 of The embankment wall 23 is made of resin, for example. In the embankment placement step ST3, one end surface 25 of the embankment wall 23 is adhered to the tape 20 on the outer peripheral side of the substrate 1 and the inner peripheral side of the annular frame 21, and the one end surface 25 is attached to the tape 20 along the entire circumference. to adhere to. In the first embodiment, the embankment wall 23 is arranged coaxially with the substrate, but in the present invention, it is not necessarily arranged coaxially.

(holding step)
8 is a side view, partly in section, showing a holding step in the method of forming the circular substrate shown in FIG. The holding step ST4 is a step of holding the substrate 1 on the holding table 41 of the cutting device 40 shown in FIG.

In Embodiment 1, in the holding step ST4, the cutting device 40 shown in FIG. Clamp frame 21 .

(liquid supply step)
9 is a perspective view showing the essential part of the liquid supply step of the method of forming the circular substrate shown in FIG. 3. FIG. FIG. 10 is a side view showing, in partial cross section, the liquid supply step of the method for forming the circular substrate shown in FIG. The liquid supply step ST5 is a step of supplying the liquid 26 to the inside of the embankment wall 23 to submerge the substrate 1 in the liquid 26 after the embankment placement step ST3 is performed.

In the first embodiment, in the liquid supply step ST5, the cutting device 40 supplies the liquid 26 to the inside of the embankment wall 23 from the liquid supply nozzle 44, as shown in FIG. In Embodiment 1, the liquid 26 is pure water. In the first embodiment, in the liquid supply step ST5, the inside of the embankment wall 23 is filled with the liquid 26, and the substrate 1 is submerged in the liquid 26 as shown in FIG.

(cutting step)
11 is a perspective view showing the main part of the cutting step of the method of forming the circular substrate shown in FIG. 3. FIG. 12 is a cross-sectional view showing the main part of the cutting step in the method of forming the circular substrate shown in FIG. 3. FIG. In the cutting step ST6, after performing the liquid supply step ST5, the circular substrate 10 is cut from the surface 2 of the substrate 1 to the tape 20 by rotating the core drill 45 having a diameter smaller than that of the substrate 1. This is the step of forming.

In the first embodiment, in the cutting step ST6, the cutting device 40 rotates the spindle 46 with the core drill 45 attached to the lower end around the axis parallel to the vertical direction. The core drill 45 includes a cylindrical hollow body 47 made of metal or the like with an upper opening closed, and a cutting edge 48 provided on the annular lower surface of the hollow body 47 . The cutting edge 48 is, for example, a whetstone in which abrasive grains are fixed with a binder, and is formed flush with the inner and outer peripheral surfaces of the hollow body 47 . The inner diameter of the hollow body 47 is equal to the outer diameter 11 of the circular substrate 10 .

In the cutting step ST6, the cutting device 40, as shown in FIGS. The cutting edge 48 is brought into contact with the surface 2 so as to straddle the half-cut groove 22 . In the cutting step ST<b>6 , the cutting device 40 brings the core drill 45 closer to the holding table 41 of the holding table 41 and causes the cutting edge 48 of the core drill 45 to cut into the substrate 1 . Thus, in Embodiment 1, the cutting step ST6 is performed while supplying the liquid 26 to the core drill 45 .

In the first embodiment, in the cutting step ST6, the cutting device 40 cuts the substrate 1 with the cutting blades 48 so that the substrate 1 can be hollowed out into a circular shape with the cutting blades 48 . In Embodiment 1, in the cutting step ST6, the cutting device 40 cuts the substrate 1 by cutting the core drill 45 (cutting blade 48) from the front surface 2 to the back surface 4 of the substrate 1, that is, cutting up to the tape 20. Then, a circular substrate 10 is cut out from the substrate 1. As shown in FIG.

Structurally, the core drill 45 is difficult to supply a large amount of the liquid 26 to the processing point where the cutting edge 48 processes the substrate 1 (that is, the contact point where the cutting edge 48 and the substrate 1 contact). Therefore, the core drill 45 does not properly dissipate the heat generated at the machining point, and this heat tends to cause problems such as a decrease in machining accuracy and abnormal wear of the cutting edge 48 .

Therefore, in the first embodiment, in the cutting step ST6, the cutting device 40 cuts the core drill 45 (cutting blade 48) from the front surface 2 to the back surface 4 of the substrate 1 until the tape 20 is reached. The approaching movement toward the holding table 41 (downward) and the separating movement away from the holding table 41 (upward) are repeated. That is, in the cutting step ST6, after the core drill 45 is cut into the surface 2 of the substrate 1, the tape 20 is repeatedly moved toward and away from the tape 20. FIG.

In the cutting step ST6, the cutting device 40 makes a close movement to move the core drill 45 downward, and when the cutting edge 48 comes into contact with the surface 2 of the substrate 1, a part of the substrate 1 is cut away, and a groove is formed on the surface 2 side. It is formed. The conditions for the close movement of the core drill 45 (for example, the speed of movement) are adjusted within a range in which the influence of heat generated at the machining point does not pose a problem. For example, when the rotation speed of the core drill 45 is 3000 rpm or more and 5000 rpm or less (for example, 4000 rpm), the proximity movement speed is set to 3 μm/second or more and 7 μm/second or less (for example, 5 μm/second). should be 3 seconds or more and 7 seconds or less (for example, 4 seconds) from the time when the cutting blade 48 and the substrate 1 come into contact with each other.

In the cutting step ST6, the cutting device 40 moves away from the core drill 45 after moving the core drill 45 closer. Thereby, the liquid 26 supplied from the liquid supply nozzle 44 flows into the groove. The conditions (for example, speed of movement, etc.) for moving the core drill 45 apart are adjusted within a range in which an appropriate amount of liquid is supplied to the inside of the groove. For example, the cutting blade 48 is moved away from the surface 2 of the substrate 1 at a speed of 10 μm/sec or more and 30 μm/sec or less (for example, 20 μm/sec), which is higher than the moving speed of approaching.

If the time required for the core drill 45 to move away from the core drill 45 is too long as compared to the time required for the core drill 45 to move closer to the core drill 45, the productivity of the circular substrate 10 will decrease. Also, if the time required for the core drill 45 to move closer to the core drill 45 becomes too long, the effect of heat generated at the machining point tends to become a problem. Therefore, the time t1 for the approaching movement of the core drill 45 and the time t2 for the separating movement of the core drill 45 are adjusted within a range that satisfies, for example, 1≤t1/t2≤15, preferably 2≤t1/t2≤10. . However, in the present invention, the conditions for moving the core drill 45 do not necessarily have to satisfy the conditions described above.

In the cutting step ST6, the cutting device 40 causes the core drill 45 to approach again after moving the core drill 45 away. As a result, a portion of the substrate 1 is further scraped off, and the grooves on the surface 2 side become deeper. In addition, the conditions for the close movement of the core drill 45 may be the same as the conditions described above, or may be different.

As described above, in the cutting step ST6, the cutting device 40 causes an appropriate amount of the liquid 26 to enter the processing point (inside the groove) by moving the core drill 45 apart. Therefore, in the first embodiment, even when the substrate 1 is processed again by the subsequent close movement in the cutting step, the heat generated at the processing point can be easily discharged appropriately. In the cutting step ST6, the cutting device 40 causes the core drill 45 to move apart again after moving the core drill 45 closer. As described above, in the first embodiment, in the cutting step ST6, the cutting device 40 repeatedly moves the core drill 45 toward and away from each other, thereby solving the problem caused by the heat generated at the machining point.

In the first embodiment, in the cutting step ST6, the cutting device 40 hollows out the substrate 1 with the core drill 45, and after forming the circular substrate 10, the substrate 1 is hollowed out a predetermined number of times with the core drill 45 in the same procedure. , a predetermined number of circular substrates 10 are formed. Note that the circular substrate 10 formed in the cutting step ST6 is adhered to the tape 20. As shown in FIG.

(removal step)
13 is a perspective view showing a main part of a removing step in the method of forming the circular substrate shown in FIG. 3. FIG. The removing step ST7 is a step of removing the circular substrate 10 from the tape 20 after performing the cutting step ST6. In the first embodiment, in the removal step ST7, after removing the embankment wall 23 from the tape 20 and removing the liquid 26, a pick-up device (not shown) separates the circular substrates 10 from the tape 20 one by one as shown in FIG. to pick up. A device is formed on the surface 12 of the circular substrate 10 formed by the method for forming a circular substrate according to the first embodiment.

As described above, in the method for forming a circular substrate according to the first embodiment, since the substrate 1 is cut by the core drill 45 in the cutting step ST6 while the substrate 1 is submerged in the liquid 26, the liquid 26 reaches the processing point. It is easy to penetrate, and it is possible to suppress deterioration of processing quality due to processing heat and abnormal wear of tools. As a result, the method for forming a circular substrate according to the first embodiment has the effect of suppressing deterioration of processing quality.

Further, in the method for forming a circular substrate according to the first embodiment, since the substrate 1 is adhered to the tape 20 , the circular substrate 10 formed from the substrate 1 is continuously adhered to the tape 20 . As a result, the method for forming a circular substrate according to the first embodiment can prevent the formed circular substrate 10 from being caught in the core drill 45 .

[Modification]
A method for forming a circular substrate according to a modification of Embodiment 1 of the present invention will be described with reference to the drawings. 14 is a flow chart showing the flow of a method for forming a circular substrate according to a modification of Embodiment 1. FIG. In addition, FIG. 14 attaches|subjects the same code|symbol to the same part as Embodiment 1, and abbreviate|omits description.

As shown in FIG. 14, the method of forming a circular substrate according to a modification is similar to that of Embodiment 1, except that the holding step ST4 is carried out after the identification mark forming step ST2, and the embankment wall placement step ST3 is carried out after the holding step ST4. It is the same as the method of forming the circular substrate. That is, in the method for forming a circular substrate according to the modification, the embankment wall placement step ST3 is performed after the holding step ST4 is performed.

In the method of forming a circular substrate according to the modification, since the substrate 1 is cut by the core drill 45 in the cutting step ST6 in a state in which the substrate 1 is submerged in the liquid 26, the liquid 26 easily enters the processing point. Similar to , there is an effect that deterioration of processing quality can be suppressed.

In addition, this invention is not limited to the said embodiment. That is, various modifications can be made without departing from the gist of the present invention.

REFERENCE SIGNS LIST 1 substrate 2 front surface 4 back surface 5 thickness 10 circular substrate 20 tape 23 bank wall 26 liquid (cutting fluid)
41 holding table 45 core drill ST1 tape application step ST3 embankment placement step ST4 holding step ST5 liquid supply step ST6 cutting step ST7 removal step

Claims (3)

A circular substrate forming method for forming a circular substrate smaller than the substrate from a substrate, comprising:
a tape attaching step of attaching a tape to the back surface of the substrate;
a holding step of holding the substrate on a holding table via the tape;
before or after carrying out the holding step, an embankment placing step of arranging an embankment surrounding the substrate on the outer peripheral side thereof and having a height higher than the thickness of the substrate;
a liquid supply step of supplying a liquid to the inside of the embankment wall to submerge the substrate after performing the embankment placement step;
a cutting step of rotating a core drill having a smaller diameter than the substrate and cutting from the surface of the substrate to the tape to form a circular substrate after performing the liquid supply step;
and a removing step of removing the circular substrate from the tape after performing the cutting step. 2. The method of forming a circular substrate according to claim 1, wherein said cutting step is performed while supplying a cutting fluid to said core drill. 3. The circular substrate according to claim 1 or 2, wherein in the cutting step, the core drill cuts into the surface of the substrate, and then repeatedly moves toward and away from the tape until it reaches the tape. Forming method.

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