JP2018014458A - Method for manufacturing circular substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a circular substrate that prevents the rim of the circular substrate from being damaged when the circular substrate is separated from a material substrate, and thereby improves the quality of the circular substrate.SOLUTION: A method includes: an annular groove formation step S2 of making a core drill having a diameter smaller than that of a bare wafer cut into a surface of the bare wafer, and forming an annular groove with depth reaching prescribed thickness on the surface; a protection member pasting step S4 for pasting a protection member on the surface; a thinning step S5 of grinding the bare wafer held by a chuck table via the protection member from the rear, thinning it until it becomes the prescribed thickness and exposing the annular groove on the rear, and separating the wafer from the bare wafer; and a departure step S6 of peeling off the protection member from the bare wafer and making the wafer depart from the bare wafer.SELECTED DRAWING: Figure 1

Description

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

  In general, device chips are formed from various wafers on which optical devices such as semiconductor devices and LEDs are formed, or various substrates such as glass substrates and ceramic substrates. Usually, a device is formed on a wafer or substrate formed to a predetermined standard size. However, in order to improve handling, or when the quality of the material substrate is defective outside a predetermined region, the material substrate is used. There is a desire to form a wafer as a small-diameter circular substrate by hollowing out a part of the substrate. For this reason, conventionally, a technique is known in which a core substrate is used to cut out and separate a part of a material substrate to quickly and inexpensively form a small-diameter circular substrate (see, for example, Patent Document 1 and Patent Document 2).

JP 2012-113801 A JP 2012-248268 A

  However, the conventional technique has a problem that the circular substrate cut out from the material substrate fits inside the core drill, or the circular substrate immediately after being cut out is separated from the core drill and scattered. For this reason, damage such as chipping (chipping) occurs at the edge of the circular substrate during the punching process, and the quality of the circular substrate may be deteriorated.

  The present invention has been made in view of the above, and when a circular substrate is separated from a material substrate, the damage of the edge of the circular substrate is suppressed and the circular substrate is manufactured with the aim of improving the quality of the circular substrate. It aims to provide a method.

  In order to solve the above-described problems and achieve the object, the present invention provides a circular substrate manufacturing method for manufacturing a circular substrate having a predetermined thickness from a material substrate, wherein the first surface, the first surface, A material substrate preparation step for preparing a material substrate having a second surface opposite to the second substrate and having a thickness greater than the predetermined thickness; and a core drill having a smaller diameter than the material substrate is cut from the first surface of the material substrate; An annular groove forming step for forming an annular groove having a depth reaching the predetermined thickness on the first surface, and a protective member attaching step for attaching a protective member to the first surface on which the annular groove is formed. And grinding the material substrate held by the chuck table via the protective member from the second surface with a grinding wheel to reduce the thickness to the predetermined thickness and exposing the annular groove to the second surface. A thinning step for separating a circular substrate from the material substrate, and the thinning step It was followed, peeling the protective member from the circular substrate, and a detachment step of detaching the circular substrate from the material substrate which has been connected with the protective member.

  According to this configuration, the circular substrate is separated from the material substrate only by forming the annular groove on the first surface of the material substrate with a core drill, and grinding from the second surface opposite to the first surface. It is possible to prevent a situation where the circular substrate is fitted into the core drill or the circular substrate is detached from the core drill and scattered. For this reason, when the circular substrate is separated from the material substrate, it is possible to form a circular substrate that suppresses breakage of the edge of the circular substrate and realizes an improvement in quality. Also, compared to the case where the material substrate is thinned in advance and then cut out to separate the circular substrate, the step of thinning the material substrate separates the circular substrate, so that the step of transporting the thin substrate can be reduced. There is also an effect that the risk of cracking the substrate due to conveyance is reduced.

  In this configuration, the mark portion may be formed on the circular substrate based on the mark indicating the orientation of the material substrate formed on the material substrate before the separation step is performed.

  According to the present invention, only the groove is formed by the core drill on the first surface of the material substrate, and the circular substrate is separated from the material substrate by grinding from the second surface opposite to the first surface. It is possible to prevent a situation in which the circular substrate is fitted inside the core drill or the circular substrate is detached from the core drill and scattered. For this reason, it is possible to form a circular substrate that suppresses breakage of the edge of the circular substrate and realizes improved quality.

FIG. 1 is a flowchart showing a procedure of a method for manufacturing a circular substrate according to the present embodiment. FIG. 2 is an external perspective view of a bare wafer which is an example of a material substrate. FIG. 3 is a perspective view of a configuration in which an annular groove is formed in the bear wafer. FIG. 4 is a side sectional view of a configuration in which an annular groove is formed in the bare wafer. FIG. 5 is a perspective view showing an example of a configuration for forming the mark portion. FIG. 6 is a perspective view showing another example of the configuration for forming the mark portion. FIG. 7 is a perspective view showing another example of the configuration for forming the mark portion. FIG. 8 is a side sectional view showing a bare wafer to which an ultraviolet curable adhesive tape is attached. FIG. 9 is a side cross-sectional view showing a configuration for grinding the back surface of the bare wafer. FIG. 10 is a side sectional view showing a state in which the wafer is detached from the bare wafer.

  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.

  FIG. 1 is a flowchart showing a procedure of a method for manufacturing a circular substrate according to the present embodiment. In the method for manufacturing a circular substrate according to this embodiment, a circular substrate having a predetermined thickness is separated from a material substrate to form the circular substrate. As shown in FIG. 1, the circular substrate manufacturing method includes a material substrate preparation step S1, an annular groove forming step S2, a mark portion forming step S3, a protective member attaching step S4, a thinning step S5, and a separation step S6. It is configured. The order of these steps is not limited to that shown in FIG. 1. For example, the order of the mark forming step S3 can be appropriately changed as long as it is between the annular groove forming step S2 and the separation step S6. Next, each of these steps will be described.

[Material substrate preparation step S1]
FIG. 2 is an external perspective view of a bare wafer which is an example of a material substrate. In the material substrate preparation step S1, a bare wafer 10 that functions as a material substrate is prepared. As shown in FIG. 2, the bear wafer 10 has a front surface (first surface) 10 a and a back surface (second surface) 10 b located on the opposite side of the front surface 10 a and is formed in a disk shape. . The wafer 10 is formed by, for example, cutting a disk-like ingot (not shown) such as silicon, sapphire, or gallium into a disk shape, and then grinding and polishing the front surface 10a and the back surface 10b. In addition, a recess (mark) 10 c indicating the crystal orientation of the bare wafer 10 is formed at the edge of the bare wafer 10. In the present embodiment, a plurality of wafers (circular substrates; described later) having a smaller diameter than the bare wafer 10 are formed from one bare wafer 10. For example, a plurality of wafers having a diameter of 1 to 3 inches are formed from the bare wafer 10 having a diameter D1 of 8 inches. Moreover, the thickness H1 of the bare wafer 10 is made thicker than the thickness (predetermined thickness) of the wafer to be formed, for example, 600 to 750 μm. Note that the shape, diameter (size), and thickness of the bare wafer 10 can be changed as appropriate, and a rectangular bear wafer may be used.

[Annular groove forming step S2]
FIG. 3 is a perspective view of a configuration in which an annular groove is formed in the bare wafer, and FIG. 4 is a side sectional view of a configuration in which the annular groove is formed in the bare wafer. As shown in FIG. 3, the prepared bare wafer 10 is placed on the chuck table 20 with the surface 10 a facing up. The chuck table 20 sucks and holds the bear wafer 10 and is configured to be rotatable together with the bear wafer 10 by a rotation mechanism (not shown). A plurality of (three in FIG. 3) annular grooves 11 are formed by the core drill 22 on the surface 10 a of the bare wafer 10 held on the chuck table 20. The core drill 22 includes a core drill main body 23 formed in a cylindrical shape and a shaft 24, and is driven to rotate around an axis 24 a of the shaft 24. A cutting blade 25 for forming an annular groove in the bare wafer 10 is provided at the tip (lower end) of the core drill body 23. The core drill 22 moves the cutting blade 25 movably in the height direction with respect to the bare wafer 10 (chuck table 20) by a lifting mechanism (not shown). For this reason, the annular groove 11 is formed in the surface 10a of the bare wafer 10 by cutting from the surface 10a of the bare wafer 10 while the cutting blade 25 rotates.

  In the present embodiment, as shown in FIG. 3, the circular region 12 defined by the annular groove 11 becomes a wafer (circular substrate) 13 which is the final manufacturing object. The diameter D2 of the circular region 12 is defined by the inner diameter D2 (FIG. 4) of the cutting blade 25 of the core drill 22. Further, as shown in FIG. 4, the cutting blade 25 cuts from the surface 10a side of the bare wafer 10 to a depth H2 reaching the thickness of the wafer 13, thereby forming the annular groove 11 having the depth H2. Further, the core drill 22 moves in the horizontal direction with respect to the bear wafer 10 (chuck table 20) by a moving mechanism (not shown). Accordingly, the annular groove 11 can be formed on the surface 10a of the bare wafer 10 by changing the position. The lifting mechanism and the moving mechanism described above may be configured such that the core drill 22 and the chuck table 20 move up and down relatively, and the chuck table 20 moves up and down.

[Mark formation step S3]
Next, the mark portions 14 are respectively formed in the circular regions 12 defined by the annular grooves 11. FIG. 5 is a perspective view showing an example of a configuration for forming the mark portion. The mark portion 14 functions as a mark for indicating the crystal orientation of the bear wafer 10, similarly to the recess 10 c of the bear wafer 10. When the circular region 12 is separated from the wafer wafer 10 as the wafer 13, the crystal orientation becomes unclear, so the mark portion 14 is formed based on the recess 10c before separation. In the present embodiment, the mark portion 14 is formed by a drill device 26 as shown in FIG. The drill device 26 rotatably holds a cutting blade 26 a having a predetermined diameter, and the cutting blade 26 a forms a concave portion that becomes the mark portion 14 on the surface 10 a of the bare wafer 10 in the circular region 12. The mark portion 14 only needs to function as a mark that can determine the crystal orientation in the process of processing the wafer 13, and may be a concave portion that does not penetrate the bare wafer 10 or a through hole. Similar to the core drill 22, the drill device 26 includes a mechanism that moves up and down relative to the chuck table 20.

  Moreover, the mark part 14 can also be formed by another structure. FIG. 6 is a perspective view showing another example of the configuration for forming the mark portion. In this example, the mark portion 14 is formed on the surface 10 a of the bare wafer 10 by laser processing using the laser beam irradiation device 21. The laser beam irradiation device 21 irradiates the laser beam L toward the surface 10 a of the bare wafer 10 held on the chuck table 20. As shown in FIG. 6, the laser beam irradiation device 21 images an oscillator 27 that oscillates a laser beam L, a condenser 29 that collects the laser beam L oscillated by the oscillator 27, and the bare wafer 10 to be processed. And an alignment camera 28. In the oscillator 27, the frequency of the oscillating laser beam L is appropriately adjusted according to the type of the bare wafer 10, the processing form, and the like. The condenser 29 includes a total reflection mirror that changes the traveling direction of the laser beam L oscillated by the oscillator 27, a condenser lens that collects the laser beam L, and the like. By the laser beam L emitted from the laser beam irradiation device 21, a concave portion that becomes the mark portion 14 is formed on the surface 10 a of the bare wafer 10 in the circular region 12. Similar to the core drill 22, the laser beam irradiation device 21 includes a mechanism that moves up and down relatively with respect to the chuck table 20.

  FIG. 7 is a perspective view showing another example of the configuration for forming the mark portion. In this example, the mark portion 14 </ b> A is formed on the surface 10 a of the bare wafer 10 by cutting using the cutting device 30. As shown in FIG. 7, the cutting device 30 includes a cutting blade 32 attached to a rotary spindle 31 that is rotationally driven. Forming a groove. Similar to the core drill 22, the cutting device 30 includes a mechanism that moves up and down relative to the chuck table 20. In the example of FIG. 7, the groove portion as the mark portion 14 </ b> A is formed only inside the circular region 12, but this groove portion may extend to the bare wafer 10 outside the circular region 12.

[Protective member pasting step S4]
FIG. 8 is a side sectional view showing a bare wafer to which an ultraviolet curable adhesive tape is attached. As shown in FIG. 8, an ultraviolet curable adhesive tape 33 as a protective member is attached to the surface 10a of the bear wafer 10 in which the annular groove 11 is formed. The ultraviolet curable pressure-sensitive adhesive tape 33 is one in which the adhesive strength is reduced when the adhesive layer (adhesive layer) is irradiated with ultraviolet rays having a predetermined wavelength (300 to 400 nm), and is adhered to the surface 10 a of the bare wafer 10. 10a is protected. The ultraviolet curable adhesive tape 33 is formed in the same size and shape as the bare wafer 10 and has a substantially uniform thickness. For this reason, by sticking the ultraviolet curable adhesive tape 33 to the bare wafer 10, the ultraviolet curable adhesive tape 33 and the bare wafer 10 are integrated, the rigidity of the bare wafer 10 is improved, and the bare wafer 10 is conveyed and processed. It can be handled easily. Further, by irradiating the ultraviolet curable pressure-sensitive adhesive tape 33 with the above-described ultraviolet rays, the adhesive layer (adhesive layer) is cured and the adhesive strength is reduced, so that the ultraviolet curable pressure-sensitive adhesive tape 33 can be easily removed. Further, a glass substrate (not shown) can be used as the protective member. The glass substrate is fixed by a material that is softened by a temperature such as wax. Also with this configuration, the glass substrate can be easily removed by heating while protecting the bare wafer 10.

[Thinning step S5]
FIG. 9 is a side cross-sectional view showing a configuration for grinding the back surface of the bare wafer. Subsequently, the bare wafer 10 to which the ultraviolet curable adhesive tape 33 is attached is reversed and placed on the chuck table 20 so that the back surface 10b side of the bare wafer 10 is the upper surface. Then, the back surface 10 b side of the bare wafer 10 is ground by the grinding device 40. The grinding device 40 includes a grinding device main body 41 and a spindle 42 formed in a cylindrical shape, and is driven to rotate around an axis 42 a of the spindle 42. One or a plurality of grinding wheels 43 are annularly arranged at the front end (lower end) of the peripheral edge of the grinding apparatus main body 41. The grinding device 40 is provided at a position where the shaft center 42 a is eccentric from the shaft center 20 a of the chuck table 20, and the grinding wheel 43 is disposed so as to overlap the shaft center 20 a of the chuck table 20. According to this configuration, the grinding wheel 43 can uniformly grind the back surface 10 b of the bare wafer 10 on the chuck table 20 by rotating the chuck table 20 and the grinding device 40 around the axis. The grinding device 40 includes a mechanism that moves up and down relative to the chuck table 20.

  As shown in FIG. 9, the grinding device 40 grinds the back surface 10b of the bare wafer 10 held by the chuck table 20, and thins the bare wafer 10 until it reaches a predetermined thickness H2. Here, since the annular groove 11 is formed at the depth H2 as described above, the annular groove 11 is formed on the back surface by thinning the bare wafer 10 to the same thickness H2 as the depth H2 of the annular groove 11. 10b exposed. For this reason, the circular region 12 defined by the annular groove 11 is separated from the bare wafer 10 as a wafer 13.

[Leaving step S6]
FIG. 10 is a side sectional view showing a state in which the wafer is detached from the bare wafer. In the separation step S6, as shown in FIG. 10, the wafer 13 separated from the bare wafer 10 is separated. The wafer 13 is separated from the bare wafer 10 by grinding of the bare wafer 10, but is connected to the bare wafer 10 by an ultraviolet curable adhesive tape 33. For this reason, by irradiating the ultraviolet curable adhesive tape 33 with ultraviolet rays having a predetermined wavelength (300 to 400 nm), the adhesive layer (adhesive layer) is cured to reduce the adhesive force. According to this, since the ultraviolet curable adhesive tape 33 can be easily peeled from the wafer 13, the wafer 13 can be detached.

  According to the present embodiment, the annular groove 11 is only formed on the surface 10a of the bare wafer 10 by the core drill 22 in the annular groove forming step S2, and the wafer 13 is ground by grinding from the back surface 10b of the bare wafer 10 in the thinning step S5. Therefore, it is possible to prevent the wafer 13 from being fitted into the core drill 22 or being separated from the core drill 22 and scattered as in the conventional case. For this reason, when separating the wafer 13 from the bare wafer 10, chipping generated at the edge of the wafer 13 can be suppressed, and the quality of the wafer 13 can be improved. Further, compared to the configuration in which the bare wafer is thinned in advance and then the wafer 13 is cut out and separated, the wafer 13 is separated by the thinning step S5, so that the step of carrying the thin bare wafer can be reduced. The risk of cracking of the bear wafer is reduced.

  In addition, according to the present embodiment, the circular region 12 defined by the annular groove 11 is marked on the basis of the depression 10c indicating the crystal orientation of the bare wafer 10 formed in the bare wafer 10 before performing the separation step S6. Since the portion 14 is formed, the crystal orientation of the wafer 13 formed by separating the circular region 12 from the bare wafer 10 can be easily determined.

Next, the quality of the wafer 13 formed according to this embodiment will be described.
[Example]
A wafer wafer 10 having a diameter D1 of 8 inches and a thickness H1 of 725 μm is prepared, and an annular groove 11 having a diameter D2 of 3 inches and a depth H2 of 400 μm is formed on the surface 10a of the bare wafer 10 using a core drill 22. Three were formed. And the ultraviolet curable adhesive tape 33 was affixed on the surface 10a of the bare wafer 10, and the back surface 10b side was ground with the grinding device 40 until thickness H2 became 380 micrometers. Then, the ultraviolet curable adhesive tape 33 was irradiated with ultraviolet rays, and the wafer 13 separated by grinding was separated from the bare wafer 10. Based on this example, 30 wafers 13 were formed.

  For the formed wafer 13, for example, the evaluation of the quality of the wafer 13 was determined by measuring the size of chipping generated on the front and back edges of the wafer 13 using a microscope. Specifically, when the maximum value of the generated chipping is less than 100 μm, it is judged as good (◯), and when it is 100 μm or more, it is judged as impossible (×).

[Comparative example]
A wafer wafer having a diameter D1 of 8 inches and a thickness H1 of 380 μm was prepared, and three wafers having a diameter D2 of 3 inches were formed on the bare wafer using the core drill 22 and separated from the bare wafer. Based on this comparative example, 30 wafers were formed. For the wafer formed by the method of this comparative example, the evaluation of the quality of the wafer 13 was determined by measuring the size of chipping generated at the edge of the front surface and the back surface of the wafer 13 using a microscope.

  Table 1 is a table in which the chipping magnitudes and determination results according to the above-described examples and comparative examples are described. According to Table 1, it can be seen that the example has no difference in the chipping on the front surface side from the comparative example, but the chipping size on the back surface side is reduced as compared with the comparative example. Furthermore, the size of chipping is reduced as compared with the chipping on the surface side. In this way, the wafer 13 is separated from the bare wafer 10 by a method of separating the wafer 13 from the bare wafer 10 only by forming the annular groove 11 on the surface 10a of the bare wafer 10 with the core drill 22 and grinding from the back surface 10b of the bare wafer 10. In doing so, the size of chipping generated at the edge of the wafer 13 can be reduced, and the quality of the wafer 13 can be improved.

  As mentioned above, although one Embodiment of this invention was described, the said embodiment was shown as an example and is not intending limiting the range of invention. For example, in the present embodiment, the annular groove 11 is set to the depth H2, but the depth of the annular groove 11 is formed larger than H2, and the wafer 13 is formed by the grinding amount (height) on the back surface 10b side. You may adjust the thickness H2.

10 BEAH (having material substrate)
10a Surface (first surface)
10b Back side (second side)
11 annular groove 12 circular region 13 wafer (circular substrate)
14, 14A Marking part 20 Chuck table 21 Laser beam irradiation device 22 Core drill 27 Oscillator 29 Concentrator 33 UV curable adhesive tape (protective member)
40 Grinding machine 43 Grinding wheel

Claims (2)

A circular substrate manufacturing method for manufacturing a circular substrate of a predetermined thickness from a material substrate,
A material substrate preparing step of preparing a material substrate having a first surface and a second surface opposite to the first surface, the material substrate being thicker than the predetermined thickness;
An annular groove forming step in which a core drill having a diameter smaller than the material substrate is cut from the first surface of the material substrate, and an annular groove having a depth reaching the predetermined thickness is formed in the first surface;
A protective member attaching step of attaching a protective member to the first surface on which the annular groove is formed;
The material substrate held by the chuck table via the protective member is ground from the second surface with a grinding stone, thinned to the predetermined thickness, and the annular groove is exposed to the second surface, A thinning step for separating the circular substrate from the material substrate;
After carrying out the thinning step, the protective member is peeled off from the circular substrate, and the separation step of separating the circular substrate from the material substrate connected by the protective member;
A method of manufacturing a circular substrate comprising:   2. The circular shape according to claim 1, further comprising: a mark portion forming step for forming a mark portion on the circular substrate based on a mark indicating an orientation of the material substrate formed on the material substrate before performing the separation step. A method for manufacturing a substrate.

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