Manufacturing method of single-crystal silicon substrate

Abstract

[Problem] To provide a highly productive method for manufacturing monocrystalline silicon substrates. [Solution] After forming a release layer inside a monocrystalline silicon ingot, the monocrystalline silicon substrate is separated from the monocrystalline silicon ingot starting from this release layer. This improves the productivity of monocrystalline silicon substrate manufacturing compared to manufacturing monocrystalline silicon substrates from monocrystalline silicon ingots using a wire saw.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a single-crystal silicon substrate, which is made from a single-crystal silicon ingot, wherein the single-crystal silicon ingot is manufactured in such a way that crystal planes {100} are exposed on the front and back sides respectively. Prior Technology

[0002] Generally, semiconductor device wafers are manufactured using a disk-shaped monocrystalline silicon substrate (hereinafter referred to as "substrate"). This substrate is cut from a cylindrical monocrystalline silicon ingot (hereinafter referred to as "ingot") using a wire saw (see, for example, Patent Document 1). [Known Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-262826 Summary of the Invention

[0004] [The problem that the invention aims to solve] When cutting a substrate from a crystal ingot using a wire saw, the pre-cut material is approximately 300 μm, which is relatively large. Furthermore, the surface of the substrate cut in this way will form fine irregularities, and the substrate is bent as a whole (causing warping). Therefore, the surface of this substrate needs to be planarized by lapping, etching, and / or polishing.

[0005] In this situation, approximately two-thirds of the total silicon material used as the substrate is ultimately utilized. That is, about one-third of the total silicon material is discarded during the cutting of the substrate from the ingot and the planarization of the substrate. Therefore, productivity is low in this substrate manufacturing process using a wire saw.

[0006] In view of this, the object of the present invention is to provide a method for manufacturing a highly productive single-crystal silicon substrate.

[0007] [Technical means to solve the problem] According to the present invention, a method for manufacturing a single-crystal silicon substrate is provided, wherein the single-crystal silicon substrate is manufactured from a single-crystal silicon ingot, the single-crystal silicon ingot being manufactured such that crystal faces {100} are exposed on both the front and back sides, the method for manufacturing the single-crystal silicon substrate includes: a holding step in which the single-crystal silicon ingot with its back side placed on the holding surface of the holding platform is held by a holding platform; and a release layer forming step in which, with the focal point of a laser beam of wavelength that will penetrate the single-crystal silicon positioned inside the single-crystal silicon ingot, the laser beam is irradiated from the front side of the single-crystal silicon ingot along a first direction while the focal point is moved relative to the single-crystal silicon ingot, thereby forming a release layer in a linear region along the first direction inside the single-crystal silicon ingot, wherein the first direction is parallel to the holding surface and is perpendicular to the crystal direction of the single-crystal silicon ingot. <100> The acute angle formed between them is less than 5°; the indexing feed step, in which the position inside the single crystal silicon rod that forms the focusing point by the laser beam is moved when the peeling layer formation step is performed again along the second direction that is parallel to the holding surface and orthogonal to the first direction; and the separation step, in which the peeling layer formation step and the indexing feed step are repeatedly performed, after the peeling layer is formed from one end of the region in the second direction inside the single crystal silicon rod to the other end, the single crystal silicon substrate is separated from the single crystal silicon rod starting from the peeling layer.

[0008] Furthermore, preferably, in the stripping layer forming step, the laser beam is split in such a way that multiple focusing points are arranged along the second direction.

[0009] Furthermore, preferably, in the step of forming the release layer, the crack extends along the crystal plane, which is the crystal plane contained in the crystal plane {N10} (N is a natural number less than 10), and is parallel to the crystal direction of the single crystal silicon rod. <100> The acute angle formed between the center and the first direction is a crystal direction of less than 5°.

[0010] Furthermore, in this invention, it is preferable to repeatedly perform the peel layer forming step and the indexing feeding step, and after the peel layer is formed from the region on one end to the region on the other end, the peel layer forming step and the indexing feeding step are repeated again.

[0011] Furthermore, in this invention, it is preferable to perform the peeling layer formation step again after the peeling layer formation step and before the indexing feed step.

[0012] Furthermore, preferably, in the stripping layer forming step, the stripping layer is formed such that the width along the second direction is a predetermined length, and in the indexing feed step, the internal position of the single-crystal silicon rod that forms the focusing point by the irradiation of the laser beam is moved such that the moving distance along the second direction is greater than or equal to the predetermined length.

[0013] Furthermore, in this invention, it is preferable to include a planarization step before the holding step, in which the front side of the single-crystal silicon ingot is planarized by grinding or polishing.

[0014] [Invention Benefits] In this invention, after a release layer is formed inside the monocrystalline silicon ingot, the monocrystalline silicon substrate is separated from the monocrystalline silicon ingot starting from this release layer. This improves the productivity of monocrystalline silicon substrates compared to manufacturing them from monocrystalline silicon ingots using a wire saw. Simple Explanation of the Diagram

[0015] Figure 1 is a perspective view schematically showing an example of a single-crystal silicon rod. Figure 2 is a top view schematically showing an example of a single-crystal silicon rod. Figure 3 is a flowchart illustrating an example of a method for manufacturing a single-crystal silicon substrate. Figure 4 is a perspective view schematically showing an example of a laser processing apparatus. Figure 5 is a schematic diagram showing the travel of the laser beam in the laser beam irradiation unit. Figure 6 is a schematic top view of the crystal rod and holding stage after the holding step. Figure 7 is a schematic cross-sectional view showing the situation of irradiating a crystal rod with a laser beam. Figure 8 is a schematic cross-sectional view of adjacent release layers formed inside the crystal rod. Figure 9 is a schematic side view showing the separation step being performed in an ultrasonic application device. Figure 10 is a diagram showing the width of the peeling layer formed inside the crystal rod when a laser beam is irradiated into a straight area along its respective crystal orientation. Implementation

[0016] Referring to the accompanying drawings, embodiments of the present invention will be described. FIG1 is a perspective view schematically showing an example of a single-crystal silicon rod, and FIG2 is a top view schematically showing an example of a single-crystal silicon rod. Furthermore, FIG1 also shows the crystal planes of the single-crystal silicon exposed in the plane contained in this rod. And FIG2 also shows the crystal orientation of the single-crystal silicon constituting this rod.

[0017] The crystal rod 11 shown in Figures 1 and 2 is composed of cylindrical single-crystal silicon with crystal planes {100} (here, for convenience, we call them crystal planes (100)) exposed on the front side 11a and the back side 11b respectively. That is, this crystal rod 11 is composed of cylindrical single-crystal silicon with vertical lines (crystallization axes) of the front side 11a and the back side 11b along the crystal direction

[100] .

[0018] Furthermore, although the crystal rod 11 is manufactured with the crystal surface (100) exposed on the front side 11a and the back side 11b respectively, due to processing errors during manufacturing, the front side 11a and the back side 11b may also be surfaces that are slightly inclined from the crystal surface (100). Specifically, the front side 11a and the back side 11b of the crystal rod 11 may also be surfaces with an acute angle of less than 1° formed with the crystal surface (100). That is, the crystal axis of the crystal rod 11 may also be along a direction with an acute angle of less than 1° formed with the crystal direction

[100] .

[0019] Furthermore, an orientation plane 13 is formed on the side of the crystal rod 11, and when viewed from this orientation plane 13, the center C of the crystal rod 11 is located in the crystal direction. <110> (Here, for convenience, we will set it as the crystal orientation

[011] ). That is, in this orientation plane 13, the crystal plane (011) of the single crystal silicon is exposed.

[0020] Figure 3 is a flowchart schematically illustrating an example of a method for manufacturing a monocrystalline silicon substrate from a crystal ingot 11. Specifically, in this method, after a release layer is formed inside the crystal ingot 11 using a laser processing apparatus, the substrate is peeled off from the crystal ingot 11 starting from this release layer.

[0021] Figure 4 is a perspective view schematically showing an example of a laser processing apparatus used in this method. Furthermore, the X-axis direction (left-right direction) and Y-axis direction (front-back direction) shown in Figure 4 are mutually orthogonal directions on the horizontal plane, and the Z-axis direction (up-down direction) is a direction orthogonal to both the X-axis and Y-axis directions (vertical direction).

[0022] The laser processing apparatus 2 shown in Figure 4 has a base 4 that supports all its components. A horizontal moving mechanism 6 is disposed on the upper surface of this base 4. The horizontal moving mechanism 6 has a pair of Y-axis guide rails 8 that are fixed to the upper surface of the base 4 and extend along the Y-axis direction.

[0023] A Y-axis movable plate 10 is connected to the upper surface of a pair of Y-axis guide rails 8 in a manner that allows it to slide along the pair of Y-axis guide rails 8. Furthermore, a screw 12 extending along the Y-axis direction is disposed between the pair of Y-axis guide rails 8. A motor 14 for rotating the screw 12 is connected to the front end (one end) of this screw 12.

[0024] Furthermore, a nut portion (not shown) is provided on the surface of the screw shaft 12 with a helical groove to form a ball screw. The nut portion accommodates multiple balls, which roll on the surface of the rotating screw shaft 12. That is, if the screw shaft 12 rotates, the multiple balls will circulate within the nut portion, and the nut portion will move along the Y-axis direction.

[0025] Furthermore, this nut is fixed to the lower surface of the Y-axis moving plate 10. Therefore, if the screw 12 is rotated by the motor 14, the Y-axis moving plate 10 and the nut move together along the Y-axis direction. In addition, a pair of X-axis guide rails 16 extending along the X-axis direction are fixed to the upper surface of the Y-axis moving plate 10.

[0026] An X-axis movable plate 18 is connected to the upper surface of a pair of X-axis guide rails 16 in a manner that allows it to slide along the pair of X-axis guide rails 16. Furthermore, a screw 20 extending along the X-axis direction is disposed between the pair of X-axis guide rails 16. A motor 22 for rotating the screw 20 is connected to one end of the screw 20.

[0027] Furthermore, a nut portion (not shown) is provided on the surface of the screw shaft 20 with a helical groove to form a ball screw. The nut portion accommodates multiple balls, which roll on the surface of the rotating screw shaft 20. That is, if the screw shaft 20 rotates, the multiple balls will circulate within the nut portion, and the nut portion will move along the X-axis direction.

[0028] Furthermore, this nut is fixed to the lower surface of the X-axis moving plate 18. Therefore, if the screw shaft 20 is rotated by the motor 22, the X-axis moving plate 18 and the nut move together along the X-axis direction.

[0029] A cylindrical stage base 24 is disposed on the upper surface of the X-axis moving plate 18. A holding stage 26 for holding the crystal rod 11 is disposed on the upper part of the stage base 24. This holding stage 26 has, for example, a circular upper surface (holding surface) that is parallel to the X-axis and Y-axis directions, and a porous plate 26a is exposed in this holding surface.

[0030] Furthermore, a rotary drive source (not shown) such as a motor is connected to the lower part of the worktable base 24. Then, if this rotary drive source is activated, the holding table 26 will rotate through the center of the holding surface and use a straight line parallel to the Z-axis as the axis of rotation. Furthermore, if the aforementioned horizontal movement mechanism 6 is activated, the holding table 26 will move along the X-axis and / or Y-axis.

[0031] Furthermore, the porous plate 26a is connected to a suction source (not shown) such as a vacuum pump through a flow path provided inside the holding stage 26. Then, if this suction source is activated, a negative pressure will be generated in the space near the holding surface of the holding stage 26. In this way, for example, the holding stage 26 can hold the crystal rod 11 with its back side 11b placed on the holding surface.

[0032] Furthermore, a support structure 30 is provided in the area behind the base 4, the support structure 30 having a side surface that is substantially parallel to the Y-axis and Z-axis directions. A vertical movement mechanism 32 is arranged on the side surface of this support structure 30. The vertical movement mechanism 32 then has a pair of Z-axis guide rails 34 that are fixed to the side surface of the support structure 30 and extend along the Z-axis direction.

[0033] On the front side of a pair of Z-axis guide rails 34, a Z-axis moving plate 36 is connected in a manner that allows it to slide along the pair of Z-axis guide rails 34. Furthermore, a screw (not shown) extending along the Z-axis direction is disposed between the pair of Z-axis guide rails 34. A motor 38 for rotating the screw is connected to the upper end (one end) of this screw.

[0034] Furthermore, a nut portion (not shown) is provided on the surface of the screw shaft with helical grooves to form a ball screw. The nut portion accommodates multiple balls, which roll on the surface of the rotating screw shaft. That is, if the screw shaft rotates, the multiple balls will circulate within the nut portion, and the nut portion will move along the Z-axis direction.

[0035] Furthermore, this nut is fixed to the back side of the Z-axis moving plate 36. Therefore, if the screw shaft disposed between a pair of Z-axis guide rails 34 is rotated by the motor 38, the Z-axis moving plate 36 and the nut move together along the Z-axis direction.

[0036] A support 40 is fixed to the front side of the Z-axis moving plate 36. This support 40 supports a portion of the laser beam irradiation unit 42. Figure 5 is a schematic diagram showing the travel of the laser beam LB in the laser beam irradiation unit 42. Furthermore, in Figure 5, a portion of the constituent elements of the laser beam irradiation unit 42 is shown in a functional block diagram.

[0037] The laser beam irradiation unit 42 has a laser oscillator 44 fixed to the base 4. This laser oscillator 44 has, for example, Nd:YAG as the laser medium, and emits a pulsed laser beam LB with a wavelength (e.g., 1064 nm) that can penetrate single-crystal silicon.

[0038] The laser beam LB is supplied to the spatial light modulator 48 after its output is adjusted in the attenuator 46. Then, the laser beam LB is split in the spatial light modulator 48. For example, the spatial light modulator 48 splits the laser beam LB in such a way that the laser beam LB emitted from the irradiation head 52 described later forms a plurality (e.g., 5) focusing points evenly spaced along the Y-axis.

[0039] Furthermore, the laser beam LB, which is branched in the spatial light modulator 48, is reflected by the mirror 50 and guided to the irradiation head 52. The irradiation head 52 houses a focusing lens (not shown) for focusing the laser beam LB. Then, the laser beam LB focused by this focusing lens is emitted to the holding surface side of the holding stage 26.

[0040] Furthermore, as shown in Figure 4, the irradiation head 52 is disposed at the front end of the cylindrical housing 54. Moreover, a support 40 is fixed to the rear side of this housing 54. Furthermore, a camera unit 56 is fixed to the front side of this housing 54.

[0041] This camera unit 56 may include, for example, a light source such as an LED (Light Emitting Diode), an objective lens, and camera elements such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

[0042] Then, if the aforementioned vertical movement mechanism 32 is activated, the irradiation head 52, the housing 54, and the camera unit 56 move along the Z-axis. Furthermore, a cover (not shown) covering the aforementioned components is provided on the base 4. A touch panel 57 is disposed on the front surface of this cover.

[0043] This touch panel 57 is composed of an input device such as a capacitive or resistive touch sensor and a display device such as a liquid crystal display or an organic EL (Electroluminescence) display, and functions as a user interface.

[0044] In the manufacturing method of the single-crystal silicon substrate shown in Figure 3, firstly, the crystal rod 11 is held in a holding stage 26 (holding step: S1). Figure 6 is a schematic top view of the crystal rod 11 and the holding stage 26 after the holding step (S1).

[0045] The crystal ingot 11 is placed on the holding surface of the holding stage 26 with its front side 11a exposed and its back side 11b exposed. Then, a negative pressure generated by the operation of the suction source connected to the porous plate 26a is applied to the back side 11b of the crystal ingot 11. In this way, the crystal ingot 11 is held by the holding stage 26.

[0046] Furthermore, the holding stage 26 holds the crystal rod 11 such that the acute angle formed by the direction from the orientation plane 13 formed on the side of the crystal rod 11 toward the center C of the crystal rod 11 (the crystal orientation of the single crystal silicon

[011] ) and the X-axis or Y-axis is 45°. This adjustment of the position of the crystal rod 11 is performed, for example, by rotating the holding stage 26 based on the image formed by the camera unit 56 using a rotation drive source connected to the lower part of the stage base 24.

[0047] Next, the holding stage 26 and the irradiation head 52 are moved relative to each other along the X-axis while the laser beam LB is irradiated onto the crystal rod 11, thereby forming a release layer in a linear region inside the crystal rod 11 (release layer formation step: S2). For example, in the release layer formation step (S2), the holding stage 26 is moved along the X-axis while the laser beam LB is irradiated onto the crystal rod 11.

[0048] Figure 7 is a schematic cross-sectional view showing the situation where a laser beam LB is irradiated onto the crystal rod 11 from the front side 11a. This crystal rod 11 is held by the holding stage 26, for example, with the crystal direction

[010] of the single crystal silicon parallel to the X-axis direction (see Figures 2 and 6, etc.). Therefore, the laser beam LB is irradiated along the crystal direction

[010] of the single crystal silicon.

[0049] Furthermore, the laser beam LB is split and irradiated with its multiple focal points positioned inside the crystal rod 11. Then, with each of the multiple focal points as the center, a modified region 15a with a disordered crystal structure of single-crystal silicon is formed inside the crystal rod 11. That is, multiple modified regions 15a are formed as if arranged along the Y-axis direction.

[0050] At this point, cracks 15b extend from each of the plurality of modified regions 15a along a predetermined crystal plane. As a result, a release layer 15 is formed inside the crystal rod 11, the release layer 15 comprising the plurality of modified regions 15a and cracks 15b developing from each of the plurality of modified regions 15a.

[0051] Generally speaking, single-crystal silicon is most prone to cracking on crystal plane {111}, followed by crystal plane {110}. Therefore, for example, if along the crystal direction of the single-crystal silicon constituting the crystal rod... <110> (For example, if a modified region is formed from the orientation plane 13 formed on the side of the crystal rod 11 toward the center C of the crystal rod 11 (crystal direction

[011] )), many cracks will be generated extending along the crystal plane {111} from this modified region.

[0052] On the other hand, if along the crystal direction of single-crystal silicon... <100> When viewed from above, multiple modified regions are formed in a manner that is orthogonal to the direction in which the linear region extends. This results in the formation of numerous cracks extending from each of these modified regions along the crystal plane {N10} (where N is a natural number less than 10) that is parallel to the direction in which the linear region extends.

[0053] For example, as described above, if multiple modified regions 15a are formed in a straight region along the crystal direction

[010] (X-axis direction) in a direction orthogonal to the direction extending from this straight region (Y-axis direction) when viewed from above, many cracks will be generated from each of these multiple modified regions 15a extending along the crystal plane {N10} (N is a natural number less than 10) parallel to the crystal direction

[010] of the single crystal silicon.

[0054] Specifically, in the case where multiple modified regions 15a are formed, cracks become more likely to propagate in the following crystal planes. [Formula 1] [Formula 2]

[0055] Then, the acute angle formed by the crystal plane (100) exposed on the front side 11a and back side 11b of the crystal rod 11 and the crystal plane {N10} of the single crystal silicon parallel to the crystal direction

[010] of the single crystal silicon is 45° or less. On the other hand, the acute angle formed by the crystal plane (100) and the crystal plane {111} of the single crystal silicon is about 54.7°.

[0056] Therefore, in the case where the crystal rod 11 is irradiated with a laser beam LB along the crystal direction

[010] of the single crystal silicon (the former case), the release layer 15 tends to become wider and thinner compared to the case where the crystal rod 11 is irradiated with a laser beam LB along the crystal direction

[011] (the latter case). That is, the ratio (W / T) of the width (W) to the thickness (T) of the release layer 15 shown in FIG. 7 is greater in the former case than in the latter case.

[0057] Next, the position inside the crystal rod 11, which has formed a focal point by irradiation with the laser beam LB, is moved along the Y-axis (indexing feed step: S3). For example, in the indexing feed step (S3), the holding stage 26 is moved along the Y-axis (indexing feed step: S3). Furthermore, the moving distance (index, division) of the holding stage 26 along the Y-axis is, for example, set to be greater than or equal to the width (W) of the aforementioned release layer 15.

[0058] Specifically, as long as the width (W) of the release layer 15 is within a predetermined length of 250 μm to 280 μm, the graduation is set to approximately 530 μm. Next, the release layer formation step (S2) described above is performed again. Figure 8 is a schematic cross-sectional view of the adjacent release layers formed inside the crystal rod 11 by performing the second release layer formation step (S2).

[0059] In this case, a release layer 15 (release layer 15-2) is formed inside the crystal rod 11. The release layer 15 (release layer 15-2) is parallel to the release layer 15 (release layer 15-1) formed in the first release layer formation step (S1) and is separate from the release layer 15-1 in the Y-axis direction. Furthermore, the indexing feed step (S3) and the release layer formation step (S2) are repeatedly performed in such a way that the release layer 15 is formed from one end of the region in the Y-axis direction inside the crystal rod 11 to the other end.

[0060] Then, if a release layer 15 is formed from one end of the region along the Y-axis inside the crystal rod 11 to the other end (step (S4): yes), the substrate is separated from the crystal rod 11 starting from the release layer 15 (separation step: S5). Figure 9 is a side view schematically showing the separation step (S5) being performed in the ultrasonic application device.

[0061] The ultrasonic application device 58 shown in Figure 9 has a cylindrical chuck stage 60. The upper surface of this chuck stage 60 serves as a holding surface for holding the back side 11b of the crystal rod 11. An annular groove is formed on this holding surface, and an opening is formed on the bottom surface of this groove. This opening is connected to a suction source such as a vacuum pump through a flow path provided inside the chuck stage 60.

[0062] Therefore, if the attraction source is activated while the back side 11b of the crystal rod 11 is placed on the holding surface of the chuck stage 60, the chuck stage 60 will hold the crystal rod 11. Furthermore, an ultrasonic application unit 62 is provided above the chuck stage 60. This ultrasonic application unit 62 has a cylindrical vibrating member 64.

[0063] The vibrating member 64 is configured such that its lower end face faces the front face 11a of the crystal rod 11 held on the chuck stage 60. Furthermore, the vibrating member 64 has a built-in ultrasonic oscillator, by which the entire vibrating member 64 vibrates.

[0064] Furthermore, the front end (lower end) of the drive shaft 66 is fixed to the central region of the upper surface of the vibrating member 64. This drive shaft 66 is connected to a vertical moving mechanism (not shown) and a horizontal moving mechanism (not shown) that can operate independently of each other. In addition, each of the vertical moving mechanism and the horizontal moving mechanism includes, for example, a ball screw.

[0065] Then, if the vertical movement mechanism is activated, the drive shaft 66 moves vertically, and if the horizontal movement mechanism is activated, the drive shaft 66 moves horizontally. Furthermore, a liquid nozzle 68 is provided on the side of the ultrasonic application unit 62. This liquid nozzle 68 supplies liquid from an opening on its lower end face to the space between the lower end face of the vibrating member 64 and the front face 11a of the crystal rod 11.

[0066] During the separation step (S5) performed in the ultrasonic application device 58, firstly, the back side 11b of the crystal ingot 11 is placed on the holding surface of the chuck stage 60. Next, an attraction source communicating with an opening formed on the bottom surface of a groove in the holding surface of the chuck stage 60 is activated. In this way, the crystal ingot 11 is held by the chuck stage 60.

[0067] Next, the vertical movement mechanism lowers the drive shaft 66 so that the lower end face of the vibrating member 64 approaches the front face 11a of the crystal rod 11. Then, while supplying liquid from the liquid nozzle 68 into the space between the lower end face of the vibrating member 64 and the front face 11a of the crystal rod 11, the horizontal movement mechanism moves the drive shaft 66, causing the ultrasonic oscillator built into the vibrating member 64 to vibrate.

[0068] In this way, ultrasound is applied to the release layer 15 formed inside the crystal rod 11. As a result, the cracks 15b contained in the release layer 15 will extend further. For example, the cracks 15b contained in the release layer 15-1 and the cracks 15b contained in the release layer 15-2 shown in FIG. 8 extend separately, and the cracks 15b of the two will connect. As a result, the crystal rod 11 will be separated in the release layer 15 to manufacture a substrate.

[0069] In the manufacturing method of the single-crystal silicon substrate shown in Figure 3, after a release layer 15 has been formed inside the crystal ingot 11, the substrate is separated from the crystal ingot 11 starting from this release layer 15. In this way, compared with the case of manufacturing the substrate from the crystal ingot 11 using a wire saw, the productivity of the substrate can be improved.

[0070] Furthermore, in the above method, by irradiating a branched laser beam LB onto a straight region along the crystal direction

[010] , multiple modified regions 15a are formed in a manner arranged orthogonal to the direction extending from this straight region when viewed from above. In this case, the number of cracks 15b extending from each of the multiple modified regions 15a along the crystal plane {N10} (N is a natural number less than 10) parallel to the crystal direction

[010] of the single crystal silicon will increase.

[0071] Therefore, in the above method, compared to irradiating the crystal rod 11 with a laser beam LB along the crystal direction

[011] of the single crystal silicon, the release layer 15 can be wider and thinner. As a result, the amount of material discarded during the manufacture of the substrate from the crystal rod 11 can be reduced, and the productivity of the substrate can be further improved.

[0072] Furthermore, the above-described method for manufacturing a single-crystal silicon substrate is one aspect of the present invention, and the present invention is not limited to the above method. For example, the crystal rod used in the present invention for manufacturing the substrate is not limited to the crystal rod 11 shown in FIG. 1 and FIG. 2.

[0073] Specifically, in this invention, a crystal rod manufacturing substrate with notches formed on its side can also be used. Alternatively, in this invention, a crystal rod manufacturing substrate without either an orientation plane or a notch formed on its side can also be used.

[0074] Furthermore, the structure of the laser processing apparatus used in this invention is not limited to the structure of the laser processing apparatus 2 described above. For example, this invention can also be implemented using a laser processing apparatus equipped with a horizontal moving mechanism that moves the irradiation head 52 of the laser beam irradiation unit 42 along the X-axis and / or Y-axis directions.

[0075] That is, in this invention, as long as the holding stage 26 of the crystal rod 11 and the irradiation head 52 of the laser beam irradiation unit 42 that emits the laser beam LB can move relative to each other along the X-axis and Y-axis directions, there are no restrictions on its structure.

[0076] Furthermore, in this invention, the linear region inside the crystal rod 11 irradiated with the laser beam LB in the stripping layer formation step (S2) is not limited to a linear region along the crystal direction

[010] . For example, in this invention, the laser beam LB can also be irradiated into a linear region along the crystal direction

[001] .

[0077] Furthermore, when the crystal rod 11 is irradiated with a laser beam LB, cracks in the following crystal planes become more likely to propagate. [Formula 3] [Formula 4]

[0078] Furthermore, in this invention, when viewed from above, a laser beam LB can also be irradiated onto a straight area that is slightly inclined from the crystal direction

[010] or the crystal direction

[001] . This point will be explained with reference to FIG10.

[0079] Figure 10 is a graph showing the width (width (W) shown in Figure 7) of the peeling layer formed inside the crystal rod 11 when a laser beam LB is irradiated on a straight region along its respective crystal direction. In addition, the horizontal axis of this graph represents the angle formed by the direction of extension of the straight region (reference region) orthogonal to the crystal direction

[011] when viewed from above and the direction of extension of the straight region (measurement region) that is the object of measurement.

[0080] That is, when the horizontal axis of this graph is 45°, the linear area along the crystal direction

[001] becomes the measurement object. Similarly, when the horizontal axis of this graph is 135°, the linear area along the crystal direction

[010] becomes the measurement object. Furthermore, the vertical axis of this graph represents the value when the width of the stripping layer formed in the measurement area by irradiating the measurement area with a laser beam LB is divided by the width of the stripping layer formed in the reference area by irradiating the reference area with a laser beam LB.

[0081] As shown in Figure 10, the width of the release layer increases when the angle formed by the direction of extension of the reference region and the direction of extension of the measurement region is 40°~50° or 130°~140°. That is, the width of the release layer increases not only in the crystal direction

[001] or the crystal direction

[010] , but also when a laser beam LB is irradiated on a straight area along a direction with an acute angle of less than 5° with respect to such crystal directions.

[0082] Therefore, in this invention, when viewed from above, a laser beam LB can be irradiated onto a straight area that is tilted less than 5° from the crystal direction

[001] or the crystal direction

[010] .

[0083] Furthermore, in this invention, after a release layer 15 is formed in the region from one end to the other end of the crystal rod 11 in the Y-axis direction (step S4: Yes), the release layer formation step (S2) and the indexing feed step (S3) can be repeated. That is, the region from one end to the other end of the crystal rod 11 in the Y-axis direction where the release layer 15 has been formed can also be irradiated again with a laser beam LB as in the formation of the release layer 15.

[0084] In this case, the density of the modified regions 15a and the cracks 15b contained in the release layer 15 increases. As a result, the separation of the substrate from the crystal rod 11 in the separation step (S5) becomes easier.

[0085] Furthermore, in this invention, the stripping layer formation step (S2) can be performed again after the stripping layer formation step (S2) and before the indexing feed step (S3). That is, the linear region inside the crystal rod 11 where the stripping layer 15 has been formed can be irradiated again with a laser beam LB as in the formation of the stripping layer 15.

[0086] In this case, similar to the above, the separation of the substrate from the crystal rod 11 in the separation step (S5) becomes easier. Furthermore, in this case, the cracks 15b contained in the release layer 15 will extend further. That is, the width of the release layer 15 (the width (W) shown in FIG. 7) becomes wider. Therefore, in this case, the moving distance (indexing) of the holding stage 26 along the Y-axis in the indexing feed step (S3) can be increased.

[0087] Furthermore, in this invention, the front surface 11a of the crystal ingot 11 can also be planarized (planarization step) by grinding or polishing before the holding step (S1). For example, this planarization can also be performed when manufacturing multiple substrates from the crystal ingot 11. Specifically, if the crystal ingot 11 is separated from the release layer 15 to manufacture the substrate, an uneven surface is formed on the newly exposed front surface of the crystal ingot 11, the uneven surface reflecting the distribution of the modified regions 15a and cracks 15b contained in the release layer 15.

[0088] Therefore, in the case of manufacturing a new substrate from the crystal rod 11, it is preferable to planarize the front side of the crystal rod 11 before the holding step (S1). This can suppress the diffusion of the laser beam LB irradiated on the crystal rod 11 in the front side of the crystal rod 11 during the release layer formation step (S2).

[0089] Similarly, in this invention, the surface of the substrate separated from the crystal rod 11 on the side of the release layer 15 can also be planarized by grinding or polishing. Furthermore, the structure and method of the above-described embodiments can be appropriately modified and implemented without departing from the purpose of this invention.

[0090] 11: Crystal rod 11a: Front 11b: Back 13: Orientation Plane 15: Peel-off layer 15a: Modified Zone 15b: Cracks 15-1: Peeling layer 15-2: Peeling layer 2: Laser processing equipment 4:Abutment 6: Horizontal moving mechanism 8: Y-axis guide rail 10: Y-axis moving plate 12: Screw 14: Motor 16: X-axis guide rail 18: X-axis moving plate 20: Screw 22: Motor 24: Workbench base 26: Chuck stage (holding unit) 26a: Maintain surface 30: Support structure 32: Vertical moving mechanism 34: Z-axis guide rail 36: Z-axis moving plate 38: Motor 40: Support 42: Laser beam illumination unit 44: Laser Oscillator 46: Attenuator 48: Spatial Light Modulator 50: Mirror 52: Irradiation head 54: Outer shell 56: Camera Unit 57: Touch panel 58: Ultrasonic application device 60: Chuck Table 62: Ultrasonic application unit 64: Vibrating components 66: Drive shaft 68: Liquid Nozzle

Claims

1. A method for manufacturing a single-crystal silicon substrate, comprising: manufacturing the single-crystal silicon substrate from a single-crystal silicon ingot, wherein the single-crystal silicon ingot is manufactured such that crystal faces {100} are exposed on both the front and back sides; the method comprising: a holding step, wherein the single-crystal silicon ingot having its back side placed on a holding surface of the holding stage is held by a holding stage; and a release layer forming step, wherein, with the focal point of a laser beam of wavelength penetrating the single-crystal silicon positioned inside the single-crystal silicon ingot, the laser beam is irradiated from the front side of the single-crystal silicon ingot along a first direction while the focal point is moved relative to the single-crystal silicon ingot, thereby forming a release layer in a linear region along the first direction inside the single-crystal silicon ingot, wherein... The first direction is parallel to the holding surface, and the acute angle formed between it and the crystal direction <100> of the single crystal silicon rod is less than 5°; the indexing feed step, in which the position inside the single crystal silicon rod that forms the focusing point by the irradiation of the laser beam is moved when the peeling layer formation step is performed again along the second direction that is parallel to the holding surface and orthogonal to the first direction; and the separation step, in which the peeling layer formation step and the indexing feed step are repeatedly performed, and after the peeling layer is formed from one end of the region in the second direction inside the single crystal silicon rod to the other end, the single crystal silicon substrate is separated from the single crystal silicon rod starting from the peeling layer.

2. The method for manufacturing a single-crystal silicon substrate as claimed in claim 1, wherein, In the stripping layer formation step, the laser beam is split in such a way that multiple focusing points are arranged along the second direction.

3. A method for manufacturing a single-crystal silicon substrate as claimed in claim 1, wherein, In the peeling layer formation step, the crack extends along the crystal plane, which is the crystal plane contained in the crystal plane {N10} (N is a natural number less than 10), and the crystal direction parallel to the crystal direction <100> of the single crystal silicon rod forms an acute angle of less than 5° with the first direction.

4. A method for manufacturing a single-crystal silicon substrate as claimed in claim 1, wherein, The peeling layer forming step and the indexing feeding step are repeatedly performed. After the peeling layer is formed from the region on one end to the region on the other end, the peeling layer forming step and the indexing feeding step are repeatedly performed again.

5. A method for manufacturing a single-crystal silicon substrate as claimed in claim 1, wherein, The peeling layer formation step is performed again after the peeling layer formation step and before the indexing feed step.

6. A method for manufacturing a single-crystal silicon substrate as claimed in claim 1, wherein, In the stripping layer formation step, the stripping layer is formed such that the width along the second direction is a predetermined length. In the indexing feed step, the position inside the single-crystal silicon rod that forms the focal point by the irradiation of the laser beam is moved such that the moving distance along the second direction is greater than the predetermined length.

7. A method for manufacturing a single-crystal silicon substrate as described in any one of claims 1 to 6, wherein, Prior to the holding step, a planarization step is included, in which the front side of the single-crystal silicon ingot is planarized by grinding or polishing.

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