JP2018012133A - Manufacturing method of circular substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a circular substrate which suppresses breakage of an edge part of the circular substrate in separating the circular substrate from a material substrate to improve quality of the circular substrate.SOLUTION: A manufacturing method includes: an annular groove forming step S2 in which an annular groove of a depth of a predetermined thickness is formed by annularly irradiating a surface of a bear wafer with a laser beam having an absorptive wavelength to the bear wafer on the surface; a protective member adhering step S4 for adhering a protective member on the surface; a thinning step S5 in which the bear wafer held on a chuck table is ground through the protective member from a rear surface, is thinned to a predetermined thickness, and the annular groove is exposed from the rear surface, and a wafer is separated from the bear wafer; and a separation step S6 in which the protective member is peeled from the bear wafer and the wafer is separated from the bear 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 part of a material substrate is punched out using a core drill 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 preparing step of preparing a material substrate having an opposite second surface and having an outer diameter larger than the predetermined thickness and larger than the circular substrate; and on the first surface of the material substrate, the material substrate An annular groove forming step of irradiating a laser beam having a wavelength having an absorptivity along the outer peripheral edge of the circular substrate to form an annular groove reaching the predetermined thickness on the first surface of the material substrate; A protective member adhering step for adhering a protective member to the first surface on which the groove is formed, and the material substrate held by the chuck table via the protective member is ground from the second surface with a grinding wheel The annular groove is exposed on the second surface while being thinned to the predetermined thickness, A thinning step for separating the circular substrate from the material substrate, and after performing the thinning step, the protective member is peeled off from the circular substrate, and the circular substrate is detached from the material substrate connected by the protective member. A disengagement step.

  According to this configuration, after forming the annular groove by laser processing by laser beam irradiation, the circular substrate is separated by grinding from the back surface, so that the circular substrate that prevents damage to the edge of the circular substrate and improves quality is realized. A substrate can be formed. 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.

  The present invention is a circular substrate manufacturing method for manufacturing a circular substrate having a predetermined thickness from a material substrate, which has a first surface and a second surface opposite to the first surface, A material substrate preparing step for preparing a material substrate having a thickness greater than the thickness, and irradiating a laser beam having a wavelength transparent to the material substrate along an outer peripheral edge of the circular substrate formed on the material substrate, A modified layer forming step for forming an annular modified layer, a protective member attaching step for attaching a protective member to the first surface of the material substrate, the protective member attaching step, and the modified layer formation After the step, the material substrate held by the chuck table via the protective member is ground from the second surface with a grinding wheel to reduce the thickness to the predetermined thickness, and the modified layer is used as a starting point. A thinning step to break and separate the circular substrate from the material substrate; After performing the thinning step, and 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, after forming the annular modified layer by laser processing by laser beam irradiation, the circular substrate is separated by grinding from the back surface, so that damage to the edge of the circular substrate is suppressed and quality is improved. An realized circular substrate can be formed. 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, the circular groove is formed by laser processing by laser beam irradiation, and then the circular substrate is separated by grinding from the back surface. A substrate can be formed.

FIG. 1 is a flowchart showing a procedure of a method for manufacturing a circular substrate according to the first 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. FIG. 11 is a flowchart showing a procedure of a circular substrate manufacturing method according to the second embodiment. FIG. 12 is a perspective view of a configuration in which a modified layer is formed on a bare wafer. FIG. 13 is a side cross-sectional view of a configuration in which a modified layer is formed on a bare wafer. FIG. 14 is a perspective view illustrating an example of a configuration for forming a mark portion. FIG. 15 is a side sectional view showing a bare wafer to which an ultraviolet curable adhesive tape is attached. FIG. 16 is a side cross-sectional view showing a configuration for grinding the back surface of the bare wafer. FIG. 17 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.

[First Embodiment]
FIG. 1 is a flowchart showing a procedure of a method for manufacturing a circular substrate according to the first 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 portion 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 on the surface 10 a of the bare wafer 10 held on the chuck table 20 by 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. 3, the laser beam irradiation device 21 images an oscillator 27 that oscillates a laser beam L, a condenser 29 that condenses 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. For example, in the case of a processing mode in which the annular groove 11 is formed on the surface 10 a of the bare wafer 10, a laser beam L having a wavelength that is absorptive with respect to the bare wafer 10 is used. In the case of a processing mode in which a modified layer (described later) is formed inside the bare wafer 10, a laser beam having a wavelength that is transmissive to the bare wafer 10 is used. 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.

  The laser beam irradiation device 21 moves in a horizontal direction with respect to the bear wafer 10 (chuck table 20) by a moving mechanism (not shown). For this reason, the annular groove 11 is formed in the surface 10a of the bare wafer 10 by the relative movement of the condenser 29 along the predetermined circular orbit on the bare wafer 10 while irradiating the surface 10a of the bare wafer 10 with the laser beam L. .

  In the present embodiment, as shown in FIG. 3, the circular region 12 defined by the annular groove 11 finally becomes a wafer (circular substrate) 13 that is a manufacturing object. The diameter D2 of the circular region 12 is defined by the inner diameter D2 (FIG. 4) of the circular orbit of the irradiated laser beam L. Further, as shown in FIG. 4, the laser beam L is subjected to laser processing from the surface 10a side of the bare wafer 10 to a depth H2 reaching the thickness of the wafer 13, thereby forming an annular groove 11 having the depth H2. Further, by moving the laser beam irradiation device 27 with a moving mechanism, the annular groove 11 can be formed on the surface 10a of the bare wafer 10 by changing its position. The moving mechanism described above may be configured such that the laser beam irradiation device 27 and the chuck table 20 move relatively, and the chuck table 20 moves. Alternatively, a protective film such as a liquid resin may be applied to the surface 10a of the bare wafer 10 in advance, and then the annular groove 11 may be formed with the laser beam L to prevent debris (processing waste) generated by laser processing from adhering to the wafer 13. . In that case, the protective film is washed with debris and removed with pure water or the like before the protective member attaching step S4 described later.

[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 this embodiment, the mark part 14 is formed by the laser processing by the laser beam irradiation apparatus 21, as shown in FIG. In this configuration, the annular groove 11 and the mark portion 14 can be continuously formed on the surface 10a of the bare wafer 10, and the processing speed can be improved. 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.

  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 by the drill device 26. 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 drill device 26 moves the cutting edge 26a so as to advance and retreat in the height direction with respect to the bare wafer 10 (chuck table 20) by a lifting mechanism (not shown). The drill device 26 moves in the horizontal direction with respect to the chuck table 20 by a moving mechanism (not shown). The lifting mechanism and the moving mechanism described above may be configured such that the drill device 26 and the chuck table 20 move relatively, and the chuck table 20 moves.

  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 drill device 26, the cutting device 30 includes a mechanism that moves up and down relatively with respect 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 formed on the front surface 10a of the bare wafer 10 by laser processing by laser beam irradiation, and then the small-diameter wafer 13 is separated by grinding from the back surface 10b of the bare wafer 10. In addition, it is possible to prevent the wafer 13 from being fitted inside the core drill or the wafer 13 being separated from the core drill and scattered. 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.

[Second Embodiment]
Next, a method for manufacturing a circular substrate according to the second embodiment will be described. FIG. 11 is a flowchart showing a procedure of a circular substrate manufacturing method according to the second embodiment. As shown in FIG. 11, the circular substrate manufacturing method includes a material substrate preparation step S11, a modified layer forming step S12, a mark portion forming step S13, a protective member attaching step S14, a thinning step S15, and a separation step S16. Configured. In the first embodiment, the annular groove 11 is formed by irradiating the surface 10 a of the bare wafer 10 with the laser beam L. However, in this embodiment, the configuration is different in that the modified layer 51 is formed in the bare wafer 10. Further, the material substrate preparation step S11 is the same as the material substrate preparation step S1 described in the first embodiment, and thus the description thereof is omitted. Also in the present embodiment, the order of the steps described above is not limited to FIG. 11. For example, the order of the mark portion formation step S13 is appropriately changed as long as it is between the material substrate preparation step S11 and the separation step S16. It is possible. Next, each of these steps will be described.

[Modified layer forming step S12]
FIG. 12 is a perspective view of a configuration in which the modified layer is formed on the bare wafer, and FIG. 13 is a side sectional view of the configuration in which the modified layer is formed on the bare wafer. As shown in FIG. 12, the bare wafer 10 prepared in step S <b> 11 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 (three in FIG. 12) of annular modified layers 51 are formed by the laser beam irradiation device 27 inside the bare wafer 10 held on the chuck table 20. The modified layer 51 refers to a region where the density, refractive index, mechanical strength, and other physical characteristics of the bare wafer 10 are different from the surroundings. For example, there are (a) a melt processing region, (b) a dielectric breakdown region, (c) a refractive index change region, and there are regions where these are mixed. In this way, by forming the annular modified layer 51 on the bare wafer 10, the mechanical strength of the modified layer 51 can be changed (dropped).

  The laser beam irradiation device 27 irradiates the bare wafer 10 held on the chuck table 20 with a laser beam La having a wavelength having transparency. The laser beam irradiation device 27 moves in the horizontal direction with respect to the bare wafer 10 (chuck table 20) by a moving mechanism (not shown). For this reason, the collector 29 moves along a predetermined circular orbit on the bare wafer 10 while irradiating the bare wafer 10 with the laser beam La, thereby forming the annular modified layer 51 inside the bare wafer 10.

  In the present embodiment, as shown in FIG. 12, the circular region 12 defined by the modified layer 51 finally becomes a wafer (circular substrate) 13 that is a manufacturing object. The diameter D2 of the circular region 12 is defined by the inner diameter D2 (FIG. 13) of the circular orbit of the irradiated laser beam La. Further, as shown in FIG. 13, the laser beam La is transmitted from the surface 10a side of the bare wafer 10 to a depth H2 reaching the thickness of the wafer 13, and one or a plurality of layered layers are formed between the surface 10a and the depth H2. The modified layer 51 is formed. Further, the modified layer 51 can be formed in the bare wafer 10 by changing the position by moving the laser beam irradiation device 27 with a moving mechanism. The moving mechanism described above may be configured such that the laser beam irradiation device 27 and the chuck table 20 move relatively, and the chuck table 20 moves.

[Mark Part Formation Step S13]
Next, the mark portions 14 are respectively formed in the circular regions 12 partitioned by the modified layer 51. FIG. 14 is a perspective view illustrating an example of a configuration for forming a 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 10 before separation. In this embodiment, the mark part 14 is formed by the laser processing by the laser beam irradiation apparatus 27, as shown in FIG. Specifically, the mark portion 14 is formed by irradiating the bare wafer 10 with a laser beam L having an absorptive wavelength. In this configuration, by changing the wavelength of the laser beam, the modified layer 51 can be continuously formed inside the bare wafer 10 and the mark portion 14 can be formed on the surface 10a, thereby improving the processing speed. 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. Further, as shown in FIGS. 6 and 7 described above, the mark portions 14 and 14 </ b> A may be formed using the drill device 26 or the cutting device 30.

[Protective member attaching step S14]
FIG. 15 is a side sectional view showing a bare wafer to which an ultraviolet curable adhesive tape is attached. As shown in FIG. 15, an ultraviolet curable adhesive tape 33 as a protective member is attached to the surface 10 a of the bare wafer 10 in which the modified layer 51 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 S15]
FIG. 16 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. 16, the grinding device 40 grinds the back surface 10b of the bare wafer 10 held by the chuck table, and thins the bare wafer 10 until it reaches a predetermined thickness H2. Here, the reforming layer 51 is expanded by a crack (breaking portion 52) that reaches the surface 10 a side of the bare wafer 10 by the pressing force due to thinning, and is broken by the breaking portion 52 starting from the modifying layer 51. The For this reason, the circular region 12 defined by the modified layer 51 is separated from the bare wafer 10 as the wafer 13.

[Leaving step S16]
FIG. 17 is a side sectional view showing a state in which the wafer is detached from the bare wafer. In the separation step S16, as shown in FIG. 17, the wafer 13 separated from the bare wafer 10 is separated. Although the wafer 13 is separated from the bare wafer 10 by grinding of the bare wafer 10 and the breaking portion 52 starting from the modified layer 51, the wafer 13 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 modified layer 51 is formed inside the bare wafer 10 by laser processing by laser beam irradiation, and then the small-diameter wafer 13 is separated by grinding from the back surface 10b of the bare wafer 10. In addition, it is possible to prevent a situation in which the wafer 13 is fitted inside the core drill or the wafer 13 is separated from the core drill and scattered. 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, since the wafer 13 is separated by the thinning step S15, 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 modified layer 51 is formed on the basis of the depression 10c indicating the crystal orientation of the bare wafer 10 formed in the bare wafer 10 before the separation step S16 is performed. Since the mark 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 by the above embodiment will be described.
[Example 1]
A wafer wafer 10 having a diameter D1 of 8 inches and a thickness H1 of 725 μm is prepared, and laser processing is applied to the surface 10a of the bare wafer 10 to form an annular groove 11 having a diameter D2 of 3 inches and a depth H2 of 400 μm. Formed. And the ultraviolet curable adhesive tape 33 was affixed on the surface 10a of the bare wafer 10, and the back surface 10 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 1, 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, if the maximum value of chipping generated is less than 30 μm, it is good (◯), if it is 30 μm or more and less than 100 μm, it is acceptable (Δ), and if it is 100 μm or more, it is impossible (×). did.

[Example 2]
A wafer wafer 10 having a diameter D1 of 8 inches and a thickness H1 of 725 μm is prepared, and laser processing is applied to the inside of the bare wafer 10 to modify the diameter D2 of 3 inches and a depth H2 from the surface 10a of 400 μm. Three layers 51 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 2, 30 wafers 13 were formed.

  In the same way as in Example 1, the formed wafer 13 was evaluated for quality evaluation of the wafer 13 by measuring the size of chipping generated at the front and back edges of the wafer 13 using a microscope. .

[Comparative Example 1]
As a wafer, a wafer having a diameter D1 of 8 inches and a thickness H1 of 380 μm was prepared. Using this core wafer, three wafers having a diameter D2 of 3 inches were formed and separated from the bare wafer. Based on Comparative Example 1, 30 wafers were formed. Similarly to Example 1, the wafer formed by the method of Comparative Example 1 was also measured by measuring the size of chipping generated on the front and back edges of the wafer 13 using a microscope. Judgment of quality evaluation.

[Comparative Example 2]
A bear wafer having a diameter D1 of 8 inches and a thickness H1 of 380 μm was prepared. The bare wafer was fully cut by laser processing, and three wafers having a diameter D2 of 3 inches were formed and separated from the bare wafer. Based on Comparative Example 2, 30 wafers were formed. For the wafer formed in Comparative Example 2, as in Example 1, the quality of the wafer 13 was measured by measuring the size of chipping generated at the front and back edges of the wafer 13 using a microscope. Was evaluated.

  Table 1 is a table in which the chipping magnitudes and determination results according to the above-described Examples 1 and 2 and Comparative Examples 1 and 2 are described. According to Table 1, it can be seen that in Examples 1 and 2, the amount of chipping is reduced as compared with Comparative Examples 1 and 2. In particular, in Example 1, the range of the size of chipping generated on the back side can be narrowed. In Example 2, the size of chipping generated on the surface side can be reduced. As described above, in Example 1, since the annular groove 11 is formed on the front surface 10a of the bare wafer 10 by laser processing by laser beam irradiation, the small-diameter wafer 13 is separated by grinding from the back surface 10b of the bare wafer 10. When the wafer 13 is separated from the wafer 10, 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. In Example 2, the modified layer 51 is formed inside the bare wafer 10 by laser processing by laser beam irradiation, and then ground from the back surface 10b of the bare wafer 10 to separate the small-diameter wafer 13 from the bare wafer 10. When the wafer 13 is separated, 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 27 Oscillator 29 Condenser 33 UV curable adhesive tape (protective member)
40 Grinding machine 43 Grinding wheel 51 Modified layer 52 Broken part

Claims (3)

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 and having an outer diameter larger than the predetermined thickness and larger than the circular substrate;
The first surface of the material substrate is irradiated with a laser beam having a wavelength that is absorptive with respect to the material substrate along the outer peripheral edge of the circular substrate, and the first surface of the material substrate has a predetermined thickness. An annular groove forming step for forming an annular groove leading to
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: 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;
A modified layer forming step of irradiating a laser beam having a wavelength transmissive to the material substrate along an outer peripheral edge of a circular substrate formed on the material substrate to form an annular modified layer inside the material substrate; ,
A protective member attaching step of attaching a protective member to the first surface of the material substrate;
After performing the protective member attaching step and the modified layer forming step, the material substrate held by the chuck table via the protective member is ground from the second surface with a grinding wheel, and the predetermined thickness is obtained. A thinning step of separating the circular substrate from the material substrate by breaking the modified layer and starting from the modified layer,
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:   The mark portion forming step of forming a mark portion on the circular substrate based on a mark indicating the orientation of the material substrate formed on the material substrate before performing the separation step. Of manufacturing a circular substrate.

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