Method for manufacturing single crystal silicon substrate

Abstract

To provide a manufacturing method for a single crystal silicon substrate with high productivity.SOLUTION: After a release layer is formed inside a single crystal silicon ingot, a single crystal silicon substrate is separated from the single crystal silicon ingot starting from the release layer. Thereby, the productivity of the single crystal silicon substrate can be improved as compared with a case of manufacturing the single crystal silicon substrate from the single crystal silicon ingot using a wire saw.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a single crystal silicon substrate, in which a single crystal silicon substrate is manufactured from a single crystal silicon ingot manufactured so that a crystal plane {100} is exposed on both the front and back surfaces. [Background technology]

[0002] Semiconductor device chips are generally manufactured using a disk-shaped single crystal silicon substrate (hereinafter simply referred to as a "substrate"), which is cut from a cylindrical single crystal silicon ingot (hereinafter simply referred to as an "ingot") using, for example, a wire saw (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-262826 Summary of the Invention [Problem to be solved by the invention]

[0004] When cutting a substrate from an ingot using a wire saw, the cutting width is relatively large, about 300 μm. Furthermore, the surface of the substrate cut in this way has minute irregularities and is curved overall (the substrate warps). Therefore, the surface of the substrate needs to be flattened by lapping, etching, and / or polishing.

[0005] In this case, the amount of single crystal silicon material ultimately used for the substrate is about two-thirds of the total amount of material in the ingot. In other words, about one-third of the total amount of material in the ingot is discarded when cutting the substrate from the ingot and flattening the substrate. Therefore, productivity is low when manufacturing substrates using a wire saw in this way.

[0006] In view of this, an object of the present invention is to provide a method for manufacturing a single crystal silicon substrate with high productivity. [Means for solving the problem]

[0007] According to the present invention, a method for manufacturing a single crystal silicon substrate from a single crystal silicon ingot manufactured so that a crystal plane {100} is exposed on each of the front and back surfaces thereof includes a holding step of holding the single crystal silicon ingot, with the back surface side of the single crystal silicon ingot placed on a holding surface of a holding table, on the holding table; and a laser beam having a wavelength that transmits single crystal silicon, the laser beam being parallel to the holding surface and aligned in the crystal orientation of the single crystal silicon ingot, with the focusing point of the laser beam being positioned inside the single crystal silicon ingot. <100> a separation step of forming a peeling layer in a linear region inside the single crystal silicon ingot along the first direction by irradiating the single crystal silicon ingot with the laser beam from the surface side while moving the focal point and the single crystal silicon ingot relatively along a first direction in which the acute angle formed between them is 5° or less; an indexing step of moving a position inside the single crystal silicon ingot where the focal point is formed by irradiating the laser beam along a second direction that is parallel to the holding surface and perpendicular to the first direction when the peeling layer forming step is again performed; and a separation step of repeatedly performing the peeling layer forming step and the indexing step to form the peeling layer from a region on one end side to a region on the other end side in the second direction inside the single crystal silicon ingot, and then separating the single crystal silicon substrate from the single crystal silicon ingot using the peeling layer as a starting point.

[0008] Furthermore, in the peeling layer forming step, the laser beam is preferably split so as to generate a plurality of focal points aligned along the second direction.

[0009] In the peeling layer forming step, a crystal plane included in the crystal plane {N10} (N is an integer whose absolute value is 10 or less, excluding 0), and having a crystal orientation of the single crystal silicon ingot <100> It is preferable that the cracks extend along a crystal plane parallel to a crystal orientation that forms an acute angle with the first direction of 5° or less.

[0010] In addition, in the present invention, it is preferable to repeatedly perform the peeling layer forming step and the indexing feed step to form the peeling layer from the region on one end side to the region on the other end side, and then repeatedly perform the peeling layer forming step and the indexing feed step again.

[0011] In the present invention, it is preferable to carry out the release layer forming step again after the release layer forming step and before the indexing feed step.

[0012] Furthermore, in the peeling layer forming step, it is preferable that the peeling layer is formed so that its width along the second direction is a predetermined length, and in the indexing feed step, the position inside the single crystal silicon ingot where the focal point is formed by irradiating the laser beam is moved so that the movement distance along the second direction is equal to or greater than the predetermined length.

[0013] Preferably, the present invention further includes, before the holding step, a planarizing step of grinding or polishing the surface of the single crystal silicon ingot to make it flat. [Effects of the Invention]

[0014] In the present invention, a separation layer is formed inside a single crystal silicon ingot, and then the single crystal silicon substrate is separated from the single crystal silicon ingot using the separation layer as a starting point, thereby improving the productivity of single crystal silicon substrates compared to when single crystal silicon substrates are produced from a single crystal silicon ingot using a wire saw. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a single crystal silicon ingot. [Figure 2] FIG. 2 is a plan view schematically showing an example of a single crystal silicon ingot. [Figure 3] FIG. 3 is a flow chart schematically illustrating an example of a method for manufacturing a single crystal silicon substrate. [Figure 4] FIG. 4 is a perspective view schematically showing an example of a laser processing device. [Figure 5] FIG. 5 is a diagram schematically showing how a laser beam travels in a laser beam irradiation unit. [Figure 6] FIG. 6 is a plan view schematically showing the ingot and the holding table after the holding step. [Figure 7] FIG. 7 is a cross-sectional view schematically showing how an ingot is irradiated with a laser beam. [Figure 8] FIG. 8 is a cross-sectional view schematically showing adjacent separation layers formed inside an ingot. [Figure 9] FIG. 9 is a side view schematically showing how the separation step is performed in an ultrasonic wave applying device. [Figure 10] FIG. 10 is a graph showing the width of the exfoliation layer formed inside the ingot when the laser beam is irradiated onto linear regions each along a different crystal orientation. DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view schematically showing an example of a single crystal silicon ingot, and Fig. 2 is a plan view schematically showing an example of a single crystal silicon ingot. Fig. 1 also shows the crystal planes of the single crystal silicon exposed on the planes included in this ingot. Fig. 2 also shows the crystal orientation of the single crystal silicon constituting this ingot.

[0017] 1 and 2 is made of cylindrical single-crystal silicon with a crystal plane {100} (here, for convenience, referred to as a crystal plane (100)) exposed on each of the front surface 11a and the back surface 11b. That is, this ingot 11 is made of cylindrical single-crystal silicon with perpendicular lines (crystal axes) to each of the front surface 11a and the back surface 11b aligned along the crystal orientation <0100>.

[0018] Although the ingot 11 is manufactured so that the crystal plane (100) is exposed on each of the front surface 11a and the back surface 11b, due to processing errors during manufacturing, each of the front surface 11a and the back surface 11b may be a surface that is slightly inclined from the crystal plane (100). Specifically, each of the front surface 11a and the back surface 11b of the ingot 11 may be a surface that forms an acute angle of 1° or less with the crystal plane (100). In other words, the crystal axis of the ingot 11 may be along a direction that forms an acute angle of 1° or less with the crystal orientation

[0100] .

[0019] In addition, an orientation flat 13 is formed on the side surface of the ingot 11, and the crystal orientation as viewed from this orientation flat 13 is <110> (Here, for convenience, the crystal orientation is assumed to be

[0011] .) That is, in this orientation flat 13, the crystal plane (011) of the single crystal silicon is exposed.

[0020] 3 is a flow chart schematically illustrating an example of a method for manufacturing a single crystal silicon substrate, in which a substrate is manufactured from ingot 11. Briefly, in this method, a peeling layer is formed inside ingot 11 using a laser processing device, and then the substrate is peeled off from ingot 11 using this peeling layer as a starting point.

[0021] Fig. 4 is a perspective view showing a schematic diagram of an example of a laser processing device used in this method. Note that the X-axis direction (left-right direction) and the Y-axis direction (front-back direction) shown in Fig. 4 are directions perpendicular to each other on a horizontal plane, and the Z-axis direction (up-down direction) is a direction (vertical direction) perpendicular to both the X-axis direction and the Y-axis direction.

[0022] The laser processing device 2 shown in Fig. 4 has a base 4 that supports each of the components. A horizontal movement mechanism 6 is disposed on the upper surface of the base 4. The horizontal movement mechanism 6 is fixed to the upper surface of the base 4 and has a pair of Y-axis guide rails 8 that extend along the Y-axis direction.

[0023] A Y-axis moving plate 10 is connected to the upper surfaces of the pair of Y-axis guide rails 8 in a manner that allows it to slide along the pair of Y-axis guide rails 8. A screw shaft 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 shaft 12 is connected to the front end (one end) of this screw shaft 12.

[0024] A ball screw is formed by providing a nut portion (not shown) that houses balls that roll on the surface of the rotating screw shaft 12 on the surface of the screw shaft 12 where the spiral groove is formed. That is, when the screw shaft 12 rotates, the balls circulate inside the nut portion, and the nut portion moves along the Y-axis direction.

[0025] Furthermore, this nut portion is fixed to the underside of the Y-axis moving plate 10. Therefore, when the screw shaft 12 is rotated by the motor 14, the Y-axis moving plate 10 moves along the Y-axis direction together with the nut portion. 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 moving plate 18 is connected to the upper surfaces of the pair of X-axis guide rails 16 in a manner that allows it to slide along the pair of X-axis guide rails 16. A screw shaft 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 shaft 20 is connected to one end of the screw shaft 20.

[0027] Furthermore, a nut portion (not shown) that houses balls that roll on the surface of the rotating screw shaft 20 is provided on the surface of the screw shaft 20 on which the spiral groove is formed, thereby forming a ball screw. That is, when the screw shaft 20 rotates, the balls circulate inside the nut portion, and the nut portion moves along the X-axis direction.

[0028] Furthermore, this nut portion is fixed to the underside of the X-axis moving plate 18. Therefore, when the screw shaft 20 is rotated by the motor 22, the X-axis moving plate 18 moves along the X-axis direction together with the nut portion.

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

[0030] A rotary drive source (not shown), such as a motor, is connected to the bottom of the table base 24. When this rotary drive source operates, the holding table 26 rotates around a rotation axis that passes through the center of the holding surface and is parallel to the Z-axis direction. When the above-mentioned horizontal movement mechanism 6 operates, the holding table 26 moves along the X-axis and / or Y-axis directions.

[0031] Furthermore, the porous plate 26a is connected to a suction source (not shown), such as a vacuum pump, via a flow path or the like provided inside the holding table 26. When this suction source is activated, a negative pressure is generated in the space near the holding surface of the holding table 26. This allows the holding table 26 to hold, for example, the ingot 11 with its back surface 11b placed on the holding surface.

[0032] A support structure 30 having side surfaces that are generally parallel to the Y-axis direction and the Z-axis direction is provided on the rear region of the base 4. A vertical movement mechanism 32 is disposed on the side surface of this support structure 30. The vertical movement mechanism 32 is fixed to the side surface of the support structure 30 and has a pair of Z-axis guide rails 34 that extend along the Z-axis direction.

[0033] A Z-axis moving plate 36 is connected to the front surfaces of the pair of Z-axis guide rails 34 in a manner that allows it to slide along the pair of Z-axis guide rails 34. A screw shaft (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 shaft is connected to the upper end (one end) of this screw shaft.

[0034] A nut (not shown) that houses balls that roll on the surface of the rotating screw shaft is provided on the surface of the screw shaft where the spiral grooves are formed, forming a ball screw. That is, when the screw shaft rotates, the balls circulate inside the nut, causing the nut to move along the Z-axis direction.

[0035] Furthermore, this nut portion is fixed to the rear surface side of the Z-axis moving plate 36. Therefore, when the screw shaft disposed between the pair of Z-axis guide rails 34 is rotated by the motor 38, the Z-axis moving plate 36 moves along the Z-axis direction together with the nut portion.

[0036] A support 40 is fixed to the front surface side of the Z-axis moving plate 36. This support 40 supports a part of the laser beam irradiation unit 42. Figure 5 is a diagram showing a schematic view of the laser beam LB traveling in the laser beam irradiation unit 42. Note that in Figure 5, some of the components of the laser beam irradiation unit 42 are shown in functional blocks.

[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 or the like as a laser medium, and emits a pulsed laser beam LB with a wavelength (for example, 1064 nm) that is transmitted through single crystal silicon.

[0038] The output of this laser beam LB is adjusted by an attenuator 46, and then supplied to a spatial light modulator 48. The laser beam LB is then branched in the spatial light modulator 48. For example, the spatial light modulator 48 branches the laser beam LB so that the laser beam LB emitted from an irradiation head 52 (described later) forms a plurality of (e.g., five) focusing points arranged at equal intervals along the Y-axis direction.

[0039] Furthermore, the laser beam LB branched by the spatial light modulator 48 is reflected by a mirror 50 and guided to an irradiation head 52. This irradiation head 52 houses a condenser lens (not shown) that condenses the laser beam LB, and the like. The laser beam LB condensed by this condenser lens is then emitted toward the holding surface of the holding table 26.

[0040] 4, the irradiation head 52 is provided at the front end of a cylindrical housing 54. A support 40 is fixed to the rear side of the housing 54. Furthermore, an imaging unit 56 is fixed to the front side of the housing 54.

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

[0042] When the above-described vertical movement mechanism 32 operates, the irradiation head 52, the housing 54, and the imaging unit 56 move along the Z-axis direction. Furthermore, a cover (not shown) that covers the above-described components is provided on the base 4. A touch panel 57 is disposed on the front surface of this cover.

[0043] The touch panel 57 is configured by 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 (Electro Luminescence) display, and functions as a user interface.

[0044] 3, first, ingot 11 is held by holding table 26 (holding step: S1). Fig. 6 is a plan view schematically showing ingot 11 and holding table 26 after holding step (S1).

[0045] The ingot 11 is placed with its back surface 11b on the holding surface of the holding table 26 so that its front surface 11a is exposed. A negative pressure is applied to the back surface 11b of the ingot 11 by operating a suction source communicating with the porous plate 26a. This causes the ingot 11 to be held by the holding table 26.

[0046] Furthermore, holding table 26 holds ingot 11 so that the acute angle formed by the direction from orientation flat 13 formed on the side surface of ingot 11 toward center C of ingot 11 (crystal orientation

[0011] of single crystal silicon) and the X-axis direction or Y-axis direction is 45°. Such adjustment of the position of ingot 11 is performed, for example, by rotating holding table 26 using a rotary drive source connected to the bottom of table base 24 based on an image formed by imaging unit 56.

[0047] Next, the holding table 26 and the irradiation head 52 are moved relatively along the X-axis direction while the ingot 11 is irradiated with the laser beam LB, thereby forming a peeling layer in a linear region inside the ingot 11 (peeling layer forming step: S2). For example, in the peeling layer forming step (S2), the ingot 11 is irradiated with the laser beam LB while the holding table 26 is moved along the X-axis direction.

[0048] 7 is a cross-sectional view showing a schematic diagram of a laser beam LB being irradiated onto the ingot 11 from the surface 11a side of the ingot 11. The ingot 11 is held on a holding table 26 so that the crystal orientation

[0010] of the single crystal silicon is parallel to the X-axis direction (see FIGS. 2 and 6, etc.). Therefore, the laser beam LB is irradiated along the crystal orientation

[0010] of the single crystal silicon.

[0049] The laser beam LB is branched and irradiated with each of its multiple focal points positioned inside the ingot 11. Then, modified regions 15a in which the crystal structure of the single crystal silicon is disrupted are formed inside the ingot 11, with each of the multiple focal points as the center. That is, multiple modified regions 15a are formed aligned along the Y-axis direction.

[0050] At this time, cracks 15b propagate from each of the modified regions 15a along a predetermined crystal plane, resulting in the formation of a peeled layer 15 inside the ingot 11, the peeled layer 15 including the modified regions 15a and the cracks 15b propagating from each of the modified regions 15a.

[0051] Generally, single crystal silicon is most easily cleaved along the crystal plane {111}, and second most easily cleaved along the crystal plane {110}. <110> When a modified region is formed along the direction from the orientation flat 13 formed on the side of the ingot 11 toward the center C of the ingot 11 (crystal orientation

[0011] ), many cracks will form from this modified region extending along the crystal plane {111}.

[0052] On the other hand, the crystal orientation of single crystal silicon <100> When multiple modified regions are formed in a linear region along the line so that they are aligned in a direction perpendicular to the direction in which the linear region extends in a planar view, many cracks are generated from each of the multiple modified regions, extending along crystal planes {N10} (N is an integer with an absolute value of 10 or less, excluding 0) that are parallel to the direction in which the linear region extends.

[0053] For example, as described above, when a plurality of modified regions 15a are formed in a linear region along the crystal orientation

[0010] (X-axis direction) so that they are aligned in a direction (Y-axis direction) perpendicular to the direction in which this linear region extends in a planar view, an increasing number of cracks extend from each of the plurality of modified regions 15a along the crystal planes {N10} (N is an integer with an absolute value of 10 or less, excluding 0) that are parallel to the crystal orientation

[0010] of the single-crystal silicon.

[0054] Specifically, when a plurality of modified regions 15a are formed in this way, cracks tend to propagate in the following crystal planes.

number

number

[0055] The acute angle formed between the crystal plane (100) exposed on the front surface 11a and the back surface 11b of the ingot 11 and one of the crystal planes {N10} of the single crystal silicon that is parallel to the crystal orientation

[0010] of the single crystal silicon is 45° or less. On the other hand, the acute angle formed between the crystal plane (100) and the crystal plane {111} of the single crystal silicon is approximately 54.7°.

[0056] Therefore, when the laser beam LB is irradiated onto the ingot 11 along the crystal orientation

[0010] of the single crystal silicon (the former case), the peeling layer 15 is more likely to be wide and thin than when the laser beam LB is irradiated along the crystal orientation

[0011] (the latter case). That is, the value (W / T) of the ratio of the width (W) to the thickness (T) of the peeling layer 15 shown in Fig. 7 is larger in the former case than in the latter case.

[0057] Next, the position inside the ingot 11 where the focal point is formed by the irradiation of the laser beam LB is moved along the Y-axis direction (indexing step: S3). For example, in the indexing step (S3), the holding table 26 is moved along the Y-axis direction (indexing step: S3). Note that the movement distance (index) of the holding table 26 along the Y-axis direction is set to be, for example, equal to or greater than the width (W) of the peeling layer 15.

[0058] Specifically, if the width (W) of the separation layer 15 is a predetermined length included in the range of 250 μm to 280 μm, the index is set to about 530 μm. Next, the separation layer forming step (S2) is performed again. Figure 8 is a cross-sectional view schematically showing adjacent separation layers formed inside the ingot 11 by performing the second separation layer forming step (S2).

[0059] In this case, a peeling layer 15 (peeling layer 15-2) that is parallel to the peeling layer 15 (peeling layer 15-1) formed in the first peeling layer formation step (S1) and separated from the peeling layer 15-1 in the Y-axis direction is formed inside the ingot 11. Furthermore, the indexing and feeding step (S3) and the peeling layer formation step (S2) are repeatedly performed so that the peeling layer 15 is formed from the region on one end side to the region on the other end side in the Y-axis direction inside the ingot 11.

[0060] Then, when a peeling layer 15 is formed from one end region to the other end region in the Y-axis direction inside the ingot 11 (step (S4): YES), the substrate is separated from the ingot 11 starting from the peeling layer 15 (separation step: S5). Figure 9 is a side view schematically showing how the separation step (S5) is performed in an ultrasonic wave applying device.

[0061] 9 has a cylindrical chuck table 60. The upper surface of this chuck table 60 serves as a holding surface for holding the back surface 11b of the ingot 11. An annular groove is formed in this holding surface, and an opening is formed in the bottom surface of this groove. This opening communicates with a suction source such as a vacuum pump via a flow path provided inside the chuck table 60.

[0062] Therefore, when the suction source is operated with the back surface 11b of the ingot 11 placed on the holding surface of the chuck table 60, the chuck table 60 holds the ingot 11. In addition, an ultrasonic wave applying unit 62 is provided above the chuck table 60. This ultrasonic wave applying unit 62 has a cylindrical vibration member 64.

[0063] The vibrating member 64 is provided so that the lower end surface of the vibrating member 64 faces the surface 11a of the ingot 11 held on the chuck table 60. The vibrating member 64 also has an ultrasonic vibrator built in, and when the ultrasonic vibrator vibrates, the entire vibrating member 64 vibrates.

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

[0065] When the vertical movement mechanism operates, the drive shaft 66 moves vertically, and when the horizontal movement mechanism operates, the drive shaft 66 moves horizontally. A liquid nozzle 68 is provided on the side of the ultrasonic wave application unit 62. The liquid nozzle 68 supplies liquid from an opening provided in its lower end surface to the space between the lower end surface of the vibration member 64 and the surface 11a of the ingot 11.

[0066] When the separation step (S5) is performed in the ultrasonic applying device 58, first, the back surface 11b of the ingot 11 is placed on the holding surface of the chuck table 60. Next, a suction source communicating with an opening formed in the bottom surface of the groove in the holding surface of the chuck table 60 is operated. As a result, the ingot 11 is held by the chuck table 60.

[0067] Next, the vertical movement mechanism lowers the drive shaft 66 so that the lower end surface of the vibration member 64 approaches the surface 11a of the ingot 11. Next, liquid is supplied from the liquid nozzle 68 to the space between the lower end surface of the vibration member 64 and the surface 11a of the ingot 11, and the horizontal movement mechanism moves the drive shaft 66 to vibrate the ultrasonic vibrator built into the vibration member 64.

[0068] This applies ultrasonic waves to the delamination layer 15 formed inside the ingot 11. As a result, the cracks 15b included in the delamination layer 15 extend further. For example, the cracks 15b included in the delamination layer 15-1 and the cracks 15b included in the delamination layer 15-2 shown in FIG. 8 extend, and the two cracks 15b connect to each other. As a result, the ingot 11 is separated at the delamination layer 15, and a substrate is produced.

[0069] 3, after forming a separation layer 15 inside an ingot 11, the substrate is separated from the ingot 11 starting from this separation layer 15. This improves productivity of the substrate compared to when a substrate is produced from an ingot 11 using a wire saw.

[0070] Furthermore, in the above-described method, by irradiating a linear region along the crystal orientation

[0010] with a branched laser beam LB, a plurality of modified regions 15a are formed so as to be aligned in a direction perpendicular to the direction in which the linear region extends in a plan view. In this case, an increasing number of cracks 15b extend from each of the plurality of modified regions 15a along crystal planes {N10} (N is an integer with an absolute value of 10 or less, excluding 0) that are parallel to the crystal orientation

[0010] of the single-crystal silicon.

[0071] As a result, in the above-described method, the peeling layer 15 can be made wider and thinner than when the laser beam LB is irradiated along the crystal orientation

[0011] of the single crystal silicon on the ingot 11. As a result, the amount of material discarded when manufacturing substrates from the ingot 11 can be reduced, and the productivity of the substrates can be further improved.

[0072] The above-described method for manufacturing a single crystal silicon substrate is one embodiment of the present invention, and the present invention is not limited to the above-described method. For example, the ingot used to manufacture a substrate in the present invention is not limited to the ingot 11 shown in Figures 1 and 2.

[0073] Specifically, in the present invention, the substrate may be manufactured from an ingot having a notch formed on the side surface, or from an ingot having neither an orientation flat nor a notch formed on the side surface.

[0074] Furthermore, the structure of the laser processing device used in the present invention is not limited to the structure of the above-described laser processing device 2. For example, the present invention may be implemented using a laser processing device provided with a horizontal movement mechanism that moves the irradiation head 52 of the laser beam irradiation unit 42 and the like along the X-axis direction and / or the Y-axis direction.

[0075] That is, in the present invention, it is sufficient that the holding table 26 that holds the ingot 11 and the irradiation head 52 of the laser beam irradiation unit 42 that emits the laser beam LB can move relatively along both the X-axis and Y-axis directions, and there are no limitations on the structure for this purpose.

[0076] Furthermore, in the present invention, the linear region inside the ingot 11 irradiated with the laser beam LB in the peeling layer forming step (S2) is not limited to a linear region along the crystal orientation

[0010] . For example, in the present invention, the laser beam LB may be irradiated to a linear region along the crystal orientation

[0001] .

[0077] When the ingot 11 is irradiated with the laser beam LB in this manner, cracks tend to propagate in the following crystal planes.

number

number

[0078] Furthermore, in the present invention, the laser beam LB may be irradiated onto a linear region along a direction slightly tilted from the crystal orientation

[0010] or the crystal orientation

[0001] in plan view. This point will be described with reference to FIG.

[0079] 10 is a graph showing the width (width (W) shown in FIG. 7) of the peeled layer formed inside the ingot 11 when the laser beam LB is irradiated onto linear regions each along a different crystal orientation. The horizontal axis of this graph indicates the angle between the direction in which the linear region (reference region) perpendicular to the crystal orientation

[0011] extends and the direction in which the linear region to be measured (measurement region) extends in a plan view.

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

[0001] is the measurement target. Similarly, when the horizontal axis of this graph is 135°, the linear region along the crystal orientation

[0010] is the measurement target. Furthermore, the vertical axis of this graph represents the value obtained by dividing the width of the peeled layer formed in the measurement region by irradiating the laser beam LB onto the measurement region by the width of the peeled layer formed in the reference region by irradiating the laser beam LB onto the reference region.

[0081] 10, the width of the peeling layer increases when the angle between the direction in which the reference region extends and the direction in which the measurement region extends is 40° to 50° or 130° to 140°. That is, the width of the peeling layer increases when the laser beam LB is irradiated not only along the crystal orientation

[0001] or the crystal orientation

[0010] , but also along a linear region along a direction in which the acute angle formed with these crystal orientations is 5° or less.

[0082] Therefore, in the present invention, the laser beam LB may be irradiated onto a linear region along a direction tilted by 5° or less from the crystal orientation

[0001] or the crystal orientation

[0010] in plan view.

[0083] Furthermore, in the present invention, after the separation layer 15 is formed from one end region in the Y-axis direction to the other end region inside the ingot 11 (step S4: YES), the separation layer forming step (S2) and the indexing step (S3) may be repeated again. That is, the laser beam LB may be irradiated again from one end region in the Y-axis direction inside the ingot 11 where the separation layer 15 has already been formed to the other end region so as to form the separation layer 15.

[0084] In this case, the density of the modified regions 15a and the cracks 15b included in the separation layer 15 increases, which makes it easier to separate the substrate from the ingot 11 in the separation step (S5).

[0085] In the present invention, after the separation layer forming step (S2) and before the indexing step (S3), the separation layer forming step (S2) may be performed again. That is, the laser beam LB may be irradiated again to the linear region inside the ingot 11 where the separation layer 15 has already been formed, so as to form the separation layer 15.

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

[0087] Furthermore, in the present invention, prior to the holding step (S1), the surface 11a of the ingot 11 may be flattened by grinding or polishing (flattening step). For example, this flattening may be performed when manufacturing a plurality of substrates from the ingot 11. Specifically, when the ingot 11 is separated at the separation layer 15 to manufacture the substrates, irregularities are formed on the newly exposed surface of the ingot 11, reflecting the distribution of the modified regions 15a and cracks 15b contained in the separation layer 15.

[0088] Therefore, when a new substrate is manufactured from this ingot 11, it is preferable to flatten the surface of the ingot 11 prior to the holding step (S1), thereby suppressing diffuse reflection of the laser beam LB irradiated onto the ingot 11 at the surface of the ingot 11 in the peeling layer forming step (S2).

[0089] Similarly, in the present invention, the surface of the substrate separated from the ingot 11 on the side of the separation layer 15 may be flattened by grinding or polishing. In addition, the structures and methods according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the object of the present invention. [Explanation of symbols]

[0090] 11: Ingot (11a: front side, 11b: back side) 13: Orientation Flat 15: Peeling layer (15a: modified region, 15b: crack) 15-1: Peeling layer 15-2: Peeling layer 2: Laser processing equipment 4: Base 6: Horizontal movement mechanism 8: Y-axis guide rail 10: Y-axis moving plate 12: Screw shaft 14: Motor 16: X-axis guide rail 18: X-axis moving plate 20: Screw shaft 22: Motor 24: Table base 26: Chuck table (holding unit) (26a: holding surface) 30:Support structure 32: Vertical movement mechanism 34: Z-axis guide rail 36: Z-axis moving plate 38: Motor 40: Support 42: Laser beam irradiation unit 44: Laser oscillator 46: Attenuator 48: Spatial light modulator 50: Mirror 52: Irradiation head 54: Housing 56: Imaging unit 57: Touch panel 58: Ultrasonic wave application device 60: Chuck table 62: Ultrasonic wave application unit 64: Vibration member 66: Drive shaft 68: Liquid nozzle

Claims

1. A method for manufacturing a single crystal silicon substrate, comprising the steps of: manufacturing a single crystal silicon substrate from a single crystal silicon ingot manufactured so that a crystal plane {100} is exposed on each of a front surface and a back surface; a holding step of holding the single crystal silicon ingot, the back surface of which is placed on a holding surface of a holding table, by the holding table; a separation layer forming step of irradiating the single crystal silicon ingot from the front surface side with the laser beam while positioning a focal point of a laser beam having a wavelength that transmits single crystal silicon inside the single crystal silicon ingot inside the single crystal silicon ingot along a first direction that is parallel to the holding surface and has an acute angle formed with respect to a <100> crystal orientation of the single crystal silicon ingot of 5 degrees or less; an indexing step of moving a position inside the single crystal silicon ingot where the focal point is formed by irradiating the laser beam when the peeling layer forming step is performed again, along a second direction that is parallel to the holding surface and perpendicular to the first direction; a separation step of separating the single crystal silicon substrate from the single crystal silicon ingot starting from the peeling layer after repeatedly performing the peeling layer formation step and the indexing step to form the peeling layer from a region on one end side to a region on the other end side in the second direction inside the single crystal silicon ingot; 1. A method for producing a single crystal silicon substrate, comprising:

2. 2. The method for manufacturing a single crystal silicon substrate according to claim 1, wherein in the separation layer forming step, the laser beam is split so as to generate a plurality of focal points aligned along the second direction.

3. 3. The method for manufacturing a single crystal silicon substrate according to claim 1, wherein in the peeling layer formation step, a crack propagates along a crystal plane included in crystal plane {N10} (N is an integer excluding 0 and having an absolute value of 10 or less), the crystal plane being parallel to a crystal orientation of the single crystal silicon ingot having an acute angle of 5° or less with respect to the first direction among the crystal orientations <100>.

4. 4. A method for manufacturing a single crystal silicon substrate as described in claim 1, wherein the peeling layer forming step and the indexing step are repeatedly performed to form the peeling layer from the region on the one end side to the region on the other end side, and then the peeling layer forming step and the indexing step are repeatedly performed again.

5. 4. The method for producing a single crystal silicon substrate according to claim 1, wherein the step of forming the separation layer is carried out again after the step of forming the separation layer and before the step of indexing.

6. In the peeling layer forming step, the peeling layer is formed so that the width along the second direction has a predetermined length; 6. The method for manufacturing a single crystal silicon substrate according to claim 1, wherein in the indexing step, a position inside the single crystal silicon ingot where the focal point is formed by irradiation of the laser beam is moved so that the movement distance along the second direction is equal to or greater than the predetermined length.

7. 7. The method for producing a single crystal silicon substrate according to claim 1, further comprising, before the holding step, a planarizing step of grinding or polishing the surface of the single crystal silicon ingot to make it flat.

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