Substrate manufacturing method

Abstract

To provide a manufacturing method of a substrate, capable of facilitating separation of a substrate from a processed material such as an ingot, and reducing a probability where a large chip occurs in an outer peripheral region of the processed material at the separation.SOLUTION: Prior to a main processing step of forming a modification part and a cracking to each of a plurality of straight line region contained in a processed material, a preliminary processing step of forming a modification part to an outer peripheral region of the processed material is executed. Thus, in the main processing step, extension of the cracking in the outer peripheral region of the processed material can be promoted. As a result, separation of the substrate from the processed material in a separation step can be facilitated, and a probability that a large chip occurs in the outer peripheral region of the processed material at the separation can be reduced.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a substrate by manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface.

Background Art

[0002] Chips of semiconductor devices are generally manufactured using a columnar substrate made of a semiconductor material such as single crystal silicon or single crystal silicon carbide. This substrate is cut out from a columnar ingot using, for example, a wire saw (see, for example, Patent Document 1).

[0003] However, the cutting width when cutting out a substrate from an ingot using a wire saw is around 300 μm, which is relatively large. In addition, fine irregularities are formed on the surface of the substrate cut out in this way, and the substrate is curved as a whole (the substrate warps). Therefore, when manufacturing a chip using this substrate, it is necessary to flatten the surface by performing lapping, etching, and / or polishing on the surface of the substrate.

[0004] In this case, the amount of semiconductor material finally used as a substrate is about 2 / 3 of the total amount of the ingot. That is, about 1 / 3 of the total amount of the ingot is discarded during the cutting out of the substrate from the ingot and the flattening of the surface of the substrate. Therefore, when manufacturing a substrate using a wire saw in this way, productivity is low.

[0005] In view of this point, after forming a separation layer including a modified portion and cracks extending from the modified portion inside the ingot by irradiating the ingot with a laser beam having a wavelength that penetrates the semiconductor material from the surface side, a method of separating the substrate from the ingot starting from this separation layer has been proposed (see, for example, Patent Document 2). When a substrate is manufactured from an ingot using this method, the productivity of the substrate can be improved compared to the case of manufacturing a substrate using a wire saw from an ingot.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-262826 [Patent Document 2] Japanese Patent Publication No. 2022-25566 [Overview of the project] [Problems that the invention aims to solve]

[0007] In general, laser beam irradiation of an ingot is performed by moving the focal point where the laser beam is focused and the ingot relative to each other along a predetermined direction. When irradiating the outer region of the ingot with a laser beam, a portion of the laser beam directed towards the ingot (the former) may pass through the surface of the ingot, while the remainder (the latter) may not pass through the surface of the ingot.

[0008] In this case, the difference in refractive index between the inside and outside of the ingot causes a shift in the focal point where the former is focused and the focal point where the latter is focused. The power of the laser beam focused inside the ingot increases as the proportion of the former increases. That is, as the laser beam moves from the outside to the inside of the ingot with respect to its outer circumference, the power of the laser beam focused inside the ingot gradually increases.

[0009] Therefore, when irradiating the outer periphery of the ingot with a laser beam, the laser beam power may be unstable, potentially resulting in insufficient formation of modified areas and cracks. Furthermore, if the modified areas and cracks are not sufficiently formed in the outer periphery of the ingot, it may become difficult to separate the outer periphery from the substrate when separating the ingot.

[0010] Furthermore, even if the substrate can be separated from the ingot, there is a risk of significant chipping occurring in the outer region of the ingot during the separation process. In this case, a large amount of semiconductor material is wasted during the planarization of the substrate surface, reducing the productivity of the substrate.

[0011] In view of this, the object of the present invention is to provide a method for manufacturing a substrate that facilitates the separation of the substrate from a workpiece such as an ingot, and reduces the likelihood of large chips occurring in the outer peripheral region of the workpiece during such separation. [Means for solving the problem]

[0012] This invention One aspect According to the invention, a method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface comprises: a delamination layer formation step of irradiating the workpiece from the first surface side with a laser beam of a wavelength that penetrates the material constituting the workpiece to form a delamination layer inside the workpiece that includes a modified portion and cracks extending from the modified portion; and a separation step of separating the substrate from the workpiece using the delamination layer as the starting point after performing the delamination layer formation step, wherein the delamination layer formation step involves moving the focal point where the laser beam is focused relative to the workpiece while positioning the focal point in the outer peripheral region of the workpiece. The process includes: a preliminary processing step to form the modified portion in the outer peripheral region; a laser beam irradiation step in which, after performing the preliminary processing step, the focusing point is positioned in one of a plurality of linear regions that each extends along a first direction and are included in the workpiece, and the focusing point and the workpiece are moved relative to each other along the first direction; and an indexing feed step in which the position where the focusing point is formed and the workpiece are moved relative to each other along a second direction that is perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions. The workpiece is an ingot or a bare wafer. A method for manufacturing a substrate is provided. Furthermore, in the pre-processing step, the power of the laser beam may be adjusted so that the crack does not extend from the modified portion. Also, in the pre-processing step, the focal point may be positioned at a first depth from the first surface, and in the laser beam irradiation step, the focal point may be positioned at a second depth different from the first depth from the first surface. Moreover, the workpiece consists of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first surface and the second surface, respectively, and the first direction is parallel to the specific crystal plane and the crystal orientation <100> The angle with respect to a specific crystal orientation included in the material may be 5° or less.

[0013] According to another aspect of the present invention, a method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, comprising: a delamination layer forming step of irradiating the workpiece from the first surface side with a laser beam of a wavelength that penetrates the material constituting the workpiece to form a delamination layer inside the workpiece including a modified portion and cracks extending from the modified portion; and a separation step of separating the substrate from the workpiece using the delamination layer as a starting point after performing the delamination layer forming step, wherein the delamination layer forming step comprises a preliminary processing step of forming the modified portion in the outer peripheral region by moving the workpiece relative to the focal point where the laser beam is focused, with the focal point positioned in the outer peripheral region of the workpiece, and A method for manufacturing a substrate is provided, which includes, after performing a preliminary processing step, a laser beam irradiation step in which the focal point is positioned in one of a plurality of linear regions included in the workpiece, and the focal point is moved relative to the workpiece along the first direction; and an indexing feed step in which the position where the focal point is formed and the workpiece are moved relative to each other along a second direction that is perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions, wherein in the preliminary processing step, the power of the laser beam is adjusted so that the crack does not extend from the modified portion.In the preliminary processing step, the condensing point is positioned at a first depth from the first surface, and in the laser beam irradiation step, the condensing point is positioned at a second depth different from the first depth from the first surface. It's fine. . Furthermore, the workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively, and the first direction is parallel to the specific crystal plane and the crystal orientation <100> The angle with respect to a specific crystal orientation included in the material may be 5° or less.

[0014] According to yet another aspect of the present invention, a method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, comprising: a delamination layer forming step of irradiating the workpiece from the first surface side with a laser beam of a wavelength that penetrates the material constituting the workpiece to form a delamination layer inside the workpiece including a modified portion and cracks extending from the modified portion; and a separation step of separating the substrate from the workpiece using the delamination layer as a starting point after performing the delamination layer forming step, wherein the delamination layer forming step comprises a pre-processing step of forming the modified portion in the outer peripheral region of the workpiece by moving the focal point and the workpiece relative to each other while positioning the focal point where the laser beam is focused in the outer peripheral region of the workpiece; and after performing the pre-processing step, each A substrate manufacturing method may include: a laser beam irradiation step in which the focal point is positioned in one of a plurality of linear regions included in the workpiece and the focal point is moved relative to the workpiece along the first direction; and a main processing step in which the position where the focal point is formed and the workpiece is moved relative to the workpiece along a second direction perpendicular to the first direction and parallel to the first plane, by repeating these steps, thereby forming the modified portion and the crack in each of the plurality of linear regions, wherein in the pre-processing step the focal point is positioned at a first depth from the first plane, and in the laser beam irradiation step the focal point is positioned at a second depth different from the first depth from the first plane. The workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively, and the first direction is parallel to the specific crystal plane and the crystal orientation <100> The angle with respect to a specific crystal orientation included in the material may be 5° or less.

[0015] According to yet another aspect of the present invention, a method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, comprising: a delamination layer formation step of irradiating the workpiece from the first surface side with a laser beam of a wavelength that penetrates the material constituting the workpiece to form a delamination layer inside the workpiece that includes a modified portion and cracks extending from the modified portion; and a separation step of separating the substrate from the workpiece with respect to the delamination layer after performing the delamination layer formation step, wherein the delamination layer formation step involves positioning a focal point where the laser beam is focused in the outer peripheral region of the workpiece and moving the focal point and the workpiece relative to each other. The process includes: a preliminary processing step to form the modified portion in the outer peripheral region; a laser beam irradiation step in which, after performing the preliminary processing step, the focusing point is positioned in one of a plurality of linear regions that each extends along a first direction and are included in the workpiece, and the focusing point and the workpiece are moved relative to each other along the first direction; and an indexing feed step in which the position where the focusing point is formed and the workpiece are moved relative to each other along a second direction that is perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions. The workpiece is made of single crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on each of the first surface and the second surface, and the first direction is parallel to the specific crystal plane and forms an angle of 5° or less with a specific crystal orientation included in the crystal orientation <100>. , may be a method of manufacturing a substrate. .

Advantages of the Invention

[0016] In the present invention, prior to the main processing step of forming a modified portion and a crack in each of a plurality of linear regions included in a workpiece, a preliminary processing step of forming a modified portion in an outer peripheral region of the workpiece is performed.

[0017] Thereby, in the main processing step, the extension of cracks in the outer peripheral region of the workpiece can be promoted. As a result, the separation of the substrate from the workpiece in the separation step becomes easy, and the probability of a large chip occurring in the outer peripheral region of the workpiece during the separation can be reduced.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a perspective view schematically showing an example of an ingot. [Figure 2] FIG. 2 is a top view schematically showing an example of an ingot. [Figure 3] FIG. 3 is a flowchart schematically showing an example of a method for manufacturing a substrate by manufacturing the substrate from an ingot that becomes a workpiece. [Figure 4]FIG. 4 is a flowchart schematically showing an example of the separation layer formation step shown in FIG. 3. [Figure 5] FIG. 5 is a diagram schematically showing an example of a laser processing apparatus used when forming a separation layer inside an ingot. [Figure 6] FIG. 6 is a top view schematically showing a state in which an ingot is held on a holding table of a laser processing apparatus. [Figure 7] FIG. 7(A) is a perspective view schematically showing a state of the preprocessing step shown in FIG. 4, and FIG. 7(B) is a cross-sectional view schematically showing a modified portion formed inside the ingot in the preprocessing step shown in FIG. 4. [Figure 8] FIG. 8 is a top view schematically showing the ingot after the preprocessing step shown in FIG. 4. [Figure 9] FIG. 9 is a flowchart schematically showing an example of the main processing step shown in FIG. 4. [Figure 10] FIG. 10(A) is a top view schematically showing a state of the laser beam irradiation step shown in FIG. 9, and FIG. 10(B) is a cross-sectional view schematically showing a modified portion and cracks formed inside the ingot in the laser beam irradiation step shown in FIG. 9. [Figure 11] FIG. 11 is a top view schematically showing the ingot after the separation layer formation step shown in FIG. 3. [Figure 12] Each of FIGS. 12(A) and 12(B) is a partial cross-sectional side view schematically showing a state of an example of the separation step shown in FIG. 3. [Figure 13] FIG. 13 is a graph showing the width of a separation layer formed inside a workpiece made of single crystal silicon when a laser beam is irradiated on regions along different crystal orientations. [Figure 14] Each of FIGS. 14(A) and 14(B) is a partial cross-sectional side view schematically showing a state of another example of the separation step shown in FIG. 3.

Embodiments for Carrying Out the Invention

[0019] Embodiments of the present invention will be described with reference to the attached drawings. Figure 1 is a schematic perspective view showing an example of a cylindrical ingot made of single-crystal silicon, and Figure 2 is a schematic top view showing an example of this ingot.

[0020] Figure 1 also shows the crystal planes of the single-crystal silicon exposed in the plane contained within this ingot. Furthermore, Figure 2 shows the crystal orientation of the single-crystal silicon constituting this ingot.

[0021] In the ingot 11 shown in Figures 1 and 2, a specific crystal plane included in the crystal plane {100} (referred to here, for convenience, as crystal plane (100)) is exposed on both the circular surface (first surface) 11a and the circular back surface (second surface) 11b. That is, in this ingot 11, the perpendiculars (crystal axes) of the surface 11a and the back surface 11b are aligned with the crystal orientation

[0100] .

[0022] In addition, although the ingot 11 is manufactured so that the crystal planes (100) are exposed on both the front surface 11a and the back surface 11b, due to processing errors during manufacturing, a plane that is slightly tilted from the crystal planes (100) may be exposed on both the front surface 11a and the back surface 11b.

[0023] Specifically, the front surface 11a and back surface 11b of the ingot 11 may each have surfaces exposed that make an angle of 1° or less with respect to the crystal plane (100). In other words, the crystal axis of the ingot 11 may be aligned in a direction that makes an angle of 1° or less with respect to the crystal orientation

[0100] .

[0024] Furthermore, an orientation flat 13 is formed on the side surface 11c of the ingot 11, and the crystal orientation is as seen from this orientation flat 13. <110> The center C of the ingot 11 is located in a specific crystal orientation (for convenience, this will be referred to as crystal orientation

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

[0025] Figure 3 is a schematic flowchart illustrating an example of a substrate manufacturing method for producing a substrate from an ingot 11, which is the workpiece. In this method, first, a delamination layer is formed inside the ingot 11, which includes a modified portion and cracks extending from the modified portion (delamination layer formation step: S1).

[0026] Figure 4 is a schematic flowchart illustrating an example of the delamination layer formation step (S1). In this delamination layer formation step (S1), first, a modified area is formed in the outer peripheral region of the ingot 11 (pre-processing step: S11). Then, after performing the pre-processing step (S11), modified areas and cracks are formed in each of the multiple linear regions contained in the ingot 11 (main processing step: S12).

[0027] Furthermore, in the delamination layer formation step (S1), a laser processing device is used to form a delamination layer inside the ingot 11. Figure 5 is a schematic diagram showing an example of a laser processing device used when forming a delamination layer inside the ingot 11.

[0028] In Figure 5, the X-axis direction (first direction) and the Y-axis direction (second direction) are mutually orthogonal directions on the horizontal plane, and the Z-axis direction is a direction perpendicular to both the X-axis and Y-axis directions (vertical direction). Also, in Figure 5, some of the components of the laser processing apparatus are shown as functional blocks.

[0029] The laser processing apparatus 2 shown in Figure 5 has a disc-shaped holding table 4. This holding table 4 has, for example, a circular upper surface (holding surface) parallel to the X-axis and Y-axis directions. The holding table 4 also has a disc-shaped porous plate (not shown) whose upper surface is exposed on this holding surface.

[0030] Furthermore, this porous plate is in communication with a suction source (not shown) via a flow path or the like provided inside the holding table 4. This suction source includes, for example, an ejector. When this suction source operates, a suction force acts on the space near the holding surface of the holding table 4. As a result, for example, an ingot 11 placed on the holding surface can be held by the holding table 4.

[0031] Furthermore, the holding table 4 is connected to a rotational drive source (not shown). This rotational drive source includes, for example, a spindle and a motor. When this rotational drive source operates, the holding table 4 rotates around a straight line passing through the center of the holding surface and perpendicular to the Z-axis direction as its axis of rotation.

[0032] Furthermore, a laser beam irradiation unit 6 is provided above the holding table 4. This laser beam irradiation unit 6 has a laser oscillator 8. This laser oscillator 8 has, for example, Nd:YAG as the laser medium and irradiates a pulsed laser beam LB with a wavelength that penetrates the material (single crystal silicon) that makes up the ingot 11.

[0033] The laser beam LB is supplied to the branching unit 12 after its output (power) is adjusted in the attenuator 10. The branching unit 12 includes, for example, a spatial light modulator and / or a diffractive optical element (DOE) that includes a liquid crystal phase control element called LCoS (Liquid Crystal on Silicon).

[0034] The branching unit 12 then branches the laser beam LB, which is irradiated from the irradiation head 16 (described later) to the holding surface side of the holding table 4, so as to form multiple focal points aligned along the Y-axis.

[0035] The laser beam LB, branched in the branching unit 12, is reflected by the mirror 14 and guided to the irradiation head 16. The irradiation head 16 houses a focusing lens (not shown) for focusing the laser beam LB. The laser beam LB, focused by this focusing lens, is emitted from the central region of the lower surface of the irradiation head 16, and is projected onto the holding surface side of the holding table 4, or more precisely, directly downwards.

[0036] Furthermore, the irradiation head 16 of the laser beam irradiation unit 6 and the optical system (e.g., mirror 14) for guiding the laser beam LB to the irradiation head 16 are connected to a moving mechanism (not shown). This moving mechanism includes, for example, a ball screw. When this moving mechanism operates, the emission area of ​​the laser beam LB moves along the X-axis, Y-axis, and / or Z-axis.

[0037] Furthermore, in the laser processing apparatus 2, by operating the rotational drive source that rotates the holding table 4 and / or the movement mechanism that moves the emission area of ​​the laser beam LB, the position (coordinates) of the focal point where the laser beam LB, which is irradiated from the irradiation head 16 to the holding surface side of the holding table 4, is focused can be adjusted in the X-axis, Y-axis, and Z-axis directions.

[0038] When performing the delamination layer formation step (S1) in the laser processing apparatus 2, the holding table 4 first holds the ingot 11 with its surface 11a facing upwards. Figure 6 is a schematic top view showing how the holding table 4 of the laser processing apparatus 2 holds the ingot 11.

[0039] The ingot 11 is held on the holding table 4 in such a state that the angle between the direction from the orientation flat 13 toward the center C of the ingot 11 (crystal orientation

[0011] ) and the X-axis and Y-axis directions is 45°.

[0040] In other words, the ingot 11 is held on the holding table 4 in a state where, for example, the crystal orientation

[0010] is parallel to the X-axis direction and the crystal orientation

[0001] is parallel to the Y-axis direction. Once the ingot 11 is held on the holding table 4 in this manner, the preliminary processing step (S11) shown in Figure 4 is performed.

[0041] Figure 7(A) is a schematic perspective view showing an example of the pre-processing step (S11), and Figure 7(B) is a schematic cross-sectional view showing the modified portion formed inside the ingot 11 during the pre-processing step (S11). This pre-processing step (S11) is carried out, for example, in the following order.

[0042] Specifically, the laser beam LB emission area is first positioned directly above the outer peripheral region of the ingot 11. The outer peripheral region of the ingot 11 is the region near its side surface 11c. For example, in a plan view, the outer peripheral region of the ingot 11 is the region located between the side surface 11c of the ingot 11 and a cylindrical virtual surface located 0.5% to 3.0% inward from this side surface 11c by the diameter of the ingot.

[0043] Next, the laser beam LB emission area is raised and lowered so that the multiple focal points formed by focusing each branched laser beam LB are positioned at a height corresponding to a first depth D1 from the surface 11a of the ingot 11.

[0044] Next, the laser beam LB is irradiated from the irradiation head 16 toward the ingot 11. This laser beam LB is branched and focused to form multiple (for example, 5) focal points that are equally spaced in the Y-axis direction. At this time, the distance between adjacent pairs of focal points is set to, for example, 5 μm to 20 μm, typically 10 μm.

[0045] Furthermore, the power of the laser beam LB focused at each of the multiple focusing points, that is, the power obtained by dividing the power of the laser beam LB adjusted in the attenuator 10 by the number of branches (for example, 5), is relatively small, and is set to be, for example, between 0.1W and 0.3W, and typically 0.2W.

[0046] As a result, modified regions 15a, in which the crystal structure of single-crystal silicon is disordered, are formed in the outer region of the ingot 11, centered around each of the multiple focal points. Furthermore, when these modified regions 15a are formed, the volume of the ingot 11 expands, causing internal stress to be generated within the ingot 11.

[0047] Furthermore, if this internal stress becomes large, cracks may extend from the modified portion 15a to relieve the internal stress. However, in the preliminary processing step (S11), it is preferable that the power of the laser beam LB focused at each of the multiple focusing points is adjusted so that although the modified portion 15a is formed, cracks do not extend from the modified portion 15a.

[0048] Next, the holding table 4 is rotated once while the laser beam LB is irradiated from the irradiation head 16 toward the ingot 11. This forms a ring-shaped modified portion 15a (more specifically, multiple (e.g., 5) concentric modified portions 15a) on the outer periphery of the ingot 11.

[0049] Furthermore, in the preliminary processing step (S11), the center of the emission region of the laser beam LB may be brought closer to or further away from the center C of the ingot 11 in a plan view, and then the above-described operation may be performed again to form another modified portion 15a in the outer peripheral region of the ingot 11. This makes it possible to form a modified portion 15a over a wide area of ​​the outer peripheral region of the ingot 11.

[0050] Figure 8 is a schematic top view showing the ingot 11 after the preliminary processing step (S11) in which the above-described operation is performed three times. Note that when the preliminary processing step (S11) is performed in this manner, the width of the modified portion 15a formed in the region near the orientation flat 13 (length along the radial direction of the ingot 11) may become narrower than the width of the modified portion 15a formed in other regions.

[0051] With this in mind, in the preliminary processing step (S11), the laser beam LB may be irradiated onto the region near the orientation flat 13 with the center of the laser beam LB emission area brought close to the center C of the ingot 11 in a plan view. This makes it possible to form a modified portion 15a with a width of approximately the same size in the region near the orientation flat 13 and the other regions.

[0052] Once the preliminary processing step (S11) is completed, the main processing step (S12) shown in Figure 4 is performed. If necessary to position the ingot 11 in a predetermined orientation, the holding table 4 may be rotated prior to the main processing step (S12). For example, the holding table 4 that holds the ingot 11 may be rotated so that the crystal orientation

[0010] is parallel to the X-axis direction and the crystal orientation

[0001] is parallel to the Y-axis direction.

[0053] Figure 9 is a flowchart schematically showing an example of the main processing step (S12). In this main processing step (S12), first, a focal point where the laser beam LB is focused is positioned in one of several linear regions contained in the ingot 11, each extending along the crystal orientation

[0010] , and then the focal point and the ingot 11 are moved relative to each other along the crystal orientation

[0010] (laser beam irradiation step: S121).

[0054] Figure 10(A) is a schematic perspective view showing an example of the laser beam irradiation step (S121), and Figure 10(B) is a schematic cross-sectional view showing the modified portion and cracks formed inside the ingot 11 during the laser beam irradiation step (S121). This laser beam irradiation step (S121) is carried out, for example, in the following order.

[0055] Specifically, first, in a plan view, the laser beam LB emission region is positioned such that, with respect to the laser beam LB emission region, the region located at one end of one of the multiple linear regions contained in the ingot 11 in the Y-axis direction (crystal orientation

[0001] ) is positioned in the X-axis direction (crystal orientation

[0010] ).

[0056] Next, the laser beam LB emission area is raised and lowered so that the multiple focal points formed by focusing each branched laser beam LB are positioned at a height corresponding to a second depth D2 from the surface 11a of the ingot 11.

[0057] The second depth D2 is a different depth from the first depth D1 mentioned above; for example, it is deeper than the first depth D1. For example, the difference between the first depth D1 and the second depth D2 is greater than 0 μm and less than or equal to 120 μm.

[0058] Next, while irradiating the ingot 11 with the laser beam LB from the irradiation head 16, the emission area of ​​the laser beam LB is moved so that, in a plan view, it passes from one end to the other of the ingot 11 in the X-axis direction (crystal orientation

[0010] ).

[0059] As the laser beam LB is irradiated and the emission region of the laser beam LB moves, the multiple focal points are positioned at a second depth from the surface 11a of the ingot 11, and the multiple focal points and the ingot 11 move relative to each other along the X-axis direction (crystal orientation

[0010] ).

[0060] The laser beam LB is branched and focused to form multiple (for example, 5) focal points that are equally spaced in the Y-axis direction (crystal orientation

[0001] ). At this time, the distance between adjacent pairs of focal points is set to, for example, 5 μm to 20 μm, typically 10 μm.

[0061] Furthermore, in the laser beam irradiation step (S121), the power of the laser beam LB focused at each of the multiple focusing points is set to be greater than that in the pre-processing step (S11). For example, in the laser beam irradiation step (S121), the power of the laser beam LB focused at each of the multiple focusing points is set to be 0.3W or more and 0.6W or less, preferably 0.35W or more and 0.5W or less.

[0062] As a result, in the region located at one end of the multiple linear regions contained in the ingot 11 in the Y-axis direction (crystal orientation

[0001] ), a modified region 15b is formed in which the crystal structure of the single-crystal silicon is disordered, centered on each of the multiple focal points.

[0063] Furthermore, when the modified portion 15b is formed in this region, the volume of the ingot 11 expands, causing internal stress in the ingot 11. In addition, in this region, cracks 15c extend from the modified portion 15b to relieve this internal stress.

[0064] Furthermore, cracks 15c extending from the modified portion 15b tend to extend toward the modified portion 15a already formed in the outer peripheral region of the ingot 11, and also tend to extend across this modified portion 15a.

[0065] Then, if the laser beam LB has not yet completed irradiating all of the multiple linear regions contained in the ingot 11 (step (S122): NO), the position where the focal point is formed and the ingot 11 are moved relative to each other along the Y axis (crystal orientation

[0001] ) (indexing feed step: S123).

[0066] Specifically, in this indexing feed step (S123), the emission region of the laser beam LB is moved along the Y-axis direction (crystal orientation

[0001] ) by, for example, 300 μm to 750 μm, typically 550 μm.

[0067] Next, the laser beam irradiation step (S121) described above is performed again. Furthermore, the indexing and feeding step (S123) and the laser beam irradiation step (S121) are repeatedly performed alternately until modified portions 15b and cracks 15c are formed in all of the multiple linear regions contained in the ingot 11.

[0068] Then, once the modified portions 15b and cracks 15c are formed in all of the multiple linear regions contained in the ingot 11 (step (S122): YES), the main processing step (S12) shown in Figure 4 is completed. Figure 11 is a schematic top view of the ingot 11 after the main processing step (S12), that is, the ingot 11 after the delamination layer formation step (S1) shown in Figure 3.

[0069] When the delamination layer formation step (S1) is performed in this manner, a delamination layer 15 is formed inside the ingot 11, which includes an annular modified portion 15a formed on the outer peripheral region of the ingot 11, modified portions 15b formed in each of the multiple linear regions contained in the ingot 11, and cracks 15c (not shown in Figure 11) extending from the modified portions 15a and 15b.

[0070] Next, the substrate is separated from the ingot 11 starting from this delamination layer 15 (separation step: S2). Figures 12(A) and 12(B) are schematic partial cross-sectional side views showing an example of the separation step (S2). This separation step (S2) is carried out, for example, in the separation apparatus 18 shown in Figures 12(A) and 12(B).

[0071] The separation device 18 has a holding table 20 that holds the ingot 11 on which the peeled layer 15 is formed. The holding table 20 has a circular top surface (holding surface), on which a porous plate (not shown) is exposed.

[0072] Furthermore, this porous plate is in communication with a suction source (not shown), such as a vacuum pump, via a flow path or the like provided inside the holding table 20. When this suction source operates, a suction force acts on the space near the holding surface of the holding table 20. As a result, for example, an ingot 11 placed on the holding surface can be held by the holding table 20.

[0073] Furthermore, a separation unit 22 is provided above the holding table 20. This separation unit 22 has a cylindrical support member 24. A rotational drive source, such as a ball screw type lifting mechanism (not shown) and a motor, is connected to the upper part of this support member 24.

[0074] By operating this lifting mechanism, the separation unit 22 moves up and down. Also, by operating this rotational drive source, the support member 24 rotates with a rotation axis that passes through the center of the support member 24 and is aligned perpendicular to the holding surface of the holding table 20.

[0075] Furthermore, the lower end of the support member 24 is fixed to the center of the upper part of the disc-shaped base 26. On the lower side of the outer peripheral region of the base 26, a plurality of movable members 28 are provided at roughly equal intervals along the circumferential direction of the base 26. These movable members 28 have plate-shaped upright portions 28a that extend downward from the lower surface of the base 26.

[0076] The upper end of this upright portion 28a is connected to an actuator such as an air cylinder built into the base 26, and by operating this actuator, the movable member 28 moves along the radial direction of the base 26. In addition, a plate-shaped wedge portion 28b is provided on the inner surface of the lower end of this upright portion 28a, extending toward the center of the base 26 and becoming thinner as it approaches the tip.

[0077] In the separation device 18, for example, the separation step (S2) is carried out in the following order. Specifically, first, the ingot 11 is placed on the holding table 20 so that the center of the back surface 11b of the ingot 11 on which the peeled layer 15 is formed coincides with the center of the holding surface of the holding table 20.

[0078] Next, a suction source communicating with a porous plate exposed on the holding surface is activated so that the ingot 11 is held by the holding table 20. Then, actuators are activated to position each of the multiple movable members 28 radially outward from the base 26.

[0079] Next, the lifting mechanism is operated to position the tips of the wedge portions 28b of each of the multiple movable members 28 at a height corresponding to the peeling layer 15 formed inside the ingot 11. Then, the actuator is operated so that the wedge portions 28b are driven into the side surface 11c of the ingot 11 (see Figure 12(A)).

[0080] Next, the rotation drive source is operated so that the wedge portion 28b driven into the side surface 11c of the ingot 11 rotates. Then, the lifting mechanism is operated to raise the wedge portion 28b (see Figure 12(B)).

[0081] As described above, after driving the wedge portion 28b into the side surface 11c of the ingot 11 and rotating it, raising the wedge portion 28b further extends the cracks 15c contained in the delamination layer 15. As a result, the front surface 11a and the back surface 11b of the ingot 11 are separated. In other words, the substrate 17 is manufactured from the ingot 11, starting from the delamination layer 15.

[0082] Furthermore, if the front surface 11a and back surface 11b of the ingot 11 are separated when the wedge portion 28b is driven into the side surface 11c of the ingot 11, it is not necessary to rotate the wedge portion 28b. Alternatively, the actuator and the rotation drive source may be operated simultaneously to drive the rotating wedge portion 28b into the side surface 11c of the ingot 11.

[0083] In the substrate manufacturing method described above, prior to the main processing step (S12) in which modified portions 15b and cracks 15c are formed in each of the multiple linear regions contained in the ingot 11, a preliminary processing step (S11) is performed in which a modified portion 15a is formed in the outer peripheral region of the ingot 11.

[0084] This promotes the propagation of cracks 15c in the outer peripheral region of the ingot 11 during the main processing step (S12). As a result, the separation of the substrate 17 from the ingot 11 in the separation step (S2) becomes easier, and the likelihood of large chips occurring in the outer peripheral region of the ingot 11 during separation is reduced.

[0085] Furthermore, in the substrate manufacturing method described above, in the processing step (S12), the peeling layer 15 is formed by positioning multiple focal points of the laser beam LB, which is branched into a linear region extending along the crystal orientation

[0010] , and then moving the focal points and the ingot 11 relative to each other along the crystal orientation

[0010] .

[0086] In this case, the amount of material wasted when manufacturing the substrate 17 from the ingot 11 can be further reduced, and the productivity of the substrate 17 can be improved. This point will be explained in detail below. First, single-crystal silicon is generally most easily cleaved at a specific crystal plane included in crystal plane {111}, and second most easily cleaved at a specific crystal plane included in crystal plane {110}.

[0087] Therefore, for example, the crystal orientation of the single-crystal silicon that makes up ingot 11 <110> When a modified portion is formed along a specific crystal orientation (for example, crystal orientation

[0011] ) contained within the material, many cracks are generated from this modified portion along the specific crystal plane contained within the crystal plane {111}.

[0088] On the other hand, the crystal orientation of single-crystal silicon <100> When multiple modified regions are formed in a region along a specific crystal orientation within a given material, such that they are aligned in a direction perpendicular to the direction in which the region extends when viewed from a plan perspective, many cracks are generated from each of these modified regions along the crystal plane {N10} (where N is an integer with an absolute value of 10 or less, excluding 0) that is parallel to the direction in which the region extends.

[0089] For example, as in the substrate manufacturing method described above, if multiple modified portions 15b are formed in a region along the crystal orientation

[0010] so as to be aligned along the crystal orientation

[0001] , then many cracks 15c will extend from each of these multiple modified portions 15b along the crystal plane {N10} (where N is a natural number less than or equal to 10) that is parallel to the crystal orientation

[0010] .

[0090] Specifically, when multiple modified portions 15b are formed in this manner, cracks 15c tend to propagate more easily in the crystal planes shown in (1) and (2) below.

number

number

[0091] Furthermore, the angle that the crystal planes (100) exposed on the surface 11a and back surface 11b of the ingot 11 make with the crystal planes parallel to the crystal orientation

[0010] within the crystal plane {N10} is 45° or less. On the other hand, the angle that the crystal plane (100) makes with a specific crystal plane included in the crystal plane {111} is approximately 54.7°.

[0092] Therefore, in the above-described substrate manufacturing method, the peel layer 15 tends to be wider and thinner compared to the case where multiple modified parts are formed in a region along the crystal orientation

[0011] of the single-crystal silicon, such that they are aligned in a direction perpendicular to the direction in which the region extends when viewed in plan. As a result, in the above-described substrate manufacturing method, the amount of material discarded when manufacturing the substrate 17 from the ingot 11 can be reduced, and the productivity of the substrate 17 can be improved.

[0093] It should be noted that the above description represents only one aspect of the present invention, and the present invention is not limited to the above description. For example, the structure of the laser processing apparatus used in the present invention is not limited to the structure of the laser processing apparatus 2 described above.

[0094] For example, the present invention may be carried out using a laser processing apparatus provided with a moving mechanism for moving the holding table 4 along the X-axis, Y-axis, and / or Z-axis directions, respectively.

[0095] In other words, in the present invention, it is sufficient that the holding table 4 that holds the ingot 11 and the emission area of ​​the laser beam LB can move relative to each other along the X-axis, Y-axis, and Z-axis directions, and there are no limitations on the structure for this purpose.

[0096] Furthermore, in the preliminary processing step (S11) of the present invention, a modified portion 15a extending in a shape other than an annular shape may be formed on the outer peripheral region of the ingot 11. For example, in the preliminary processing step (S11) of the present invention, a modified portion 15a extending in a spiral or linear manner may be formed on the outer peripheral region of the ingot 11.

[0097] When forming the spirally extending modified portion 15a on the outer periphery of the ingot 11, for example, the holding table 4 can be rotated while the laser beam LB is irradiated from the irradiation head 16 toward the ingot 11, and the center of the laser beam LB emission area can be moved closer to or further away from the center C of the ingot 11 in a plan view.

[0098] Furthermore, when forming the linearly extending modified portion 15a on the outer peripheral region of the ingot 11, for example, the laser beam LB can be intermittently irradiated from the irradiation head 16 toward the ingot 11 while moving the emission region of the laser beam LB, similar to the main processing step (S12) described above.

[0099] In other words, in this case, irradiation with the laser beam LB from the irradiation head 16 is performed when the emission area of ​​the laser beam LB is located directly above the outer peripheral region of the ingot 11, and is stopped when the emission area of ​​the laser beam LB is located directly above the region surrounded by this outer peripheral region (central region).

[0100] Furthermore, in the main processing step (S12) of the present invention, the laser beam LB may be irradiated only on the central region of the ingot 11, without irradiating the outer peripheral region of the ingot 11.

[0101] In this case, irradiation with the laser beam LB from the irradiation head 16 is performed when the emission area of ​​the laser beam LB is located directly above the central region of the ingot 11, and is stopped when the emission area of ​​the laser beam LB is located directly above the outer peripheral region.

[0102] Alternatively, in the present invention's main processing step (S12), the laser beam LB may be irradiated only on the remaining outer region of the ingot 11 and the central region of the ingot 11, without irradiating a portion of the outer region of the ingot 11.

[0103] In this case, irradiation of the laser beam LB from the irradiation head 16 is initiated, for example, when the emission area of ​​the laser beam LB is moving directly above the outer peripheral region of the ingot 11 so that it is directed directly above the central region of the ingot 11, and is stopped when the emission area of ​​the laser beam LB is moving directly above the outer peripheral region of the ingot 11 so that it is directed outwards from the ingot 11.

[0104] In this processing step (S12), it is preferable to irradiate not only the central region of the ingot 11 but also at least a portion of the outer peripheral region of the ingot 11 with the laser beam LB. This makes it easier for the crack 15c formed in this processing step (S12) to extend across the modified portion 15a formed in the preliminary processing step (S11).

[0105] Furthermore, in the main processing step (S12) of the present invention, after the laser beam LB has been irradiated onto each of the plurality of linear regions contained in the ingot 11, the laser beam LB may be irradiated onto each of the plurality of linear regions again. Alternatively, in the main processing step (S12) of the present invention, the laser beam irradiation step (S121) may be performed again after the laser beam irradiation step (S121) and before the indexing feed step (S122).

[0106] In other words, in the present invention, in the processing step (S12), the laser beam LB may be irradiated again to the region where the modified portion 15b and crack 15c have already been formed to form the modified portion 15b and crack 15c. This increases the density of the modified portion 15b in each region and / or further extends the crack 15c formed in each region.

[0107] Furthermore, if the laser beam LB is irradiated multiple times to each of the multiple linear regions contained in the ingot 11, the irradiation conditions for the laser beam LB each time may be the same or different. For example, when the laser beam LB is irradiated to each region for the second time, the power of the laser beam LB focused at the focal point is adjusted to be greater than the power of the first irradiation.

[0108] Furthermore, the multiple linear regions included in the ingot 11 irradiated with the laser beam LB in the laser beam irradiation step (S121) of the present invention are not limited to regions along the crystal orientation

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

[0001] .

[0109] Furthermore, when the ingot 11 is irradiated with the laser beam LB in this manner, cracks 15c tend to propagate in the crystal planes shown in (3) and (4) below.

number

number

[0110] Furthermore, in the present invention, the laser beam LB may be irradiated in a region along a direction slightly tilted from the crystal orientation

[0010] or the crystal orientation

[0001] in a plan view. This point will be explained with reference to Figure 13.

[0111] Figure 13 is a graph showing the width of the delamination layer formed inside a workpiece made of single-crystal silicon when a laser beam LB is irradiated onto regions aligned with different crystal orientations. The horizontal axis of this graph represents the angle between the direction in which the region perpendicular to the crystal orientation

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

[0112] In other words, when the value on the horizontal axis of this graph is 45°, the region along crystal orientation

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

[0010] is the target of measurement.

[0113] Furthermore, the vertical axis of this graph shows the value obtained by dividing the width of the delamination layer formed in the measurement area by irradiating the measurement area with the laser beam LB by the width of the delamination layer formed in the reference area by irradiating the reference area with the laser beam LB.

[0114] As shown in Figure 13, the width of the delamination layer widens when the angle between the direction in which the reference region extends and the direction in which the measurement region extends is 40° or more and 50° or 130° or more and 140°. In other words, the width of the delamination layer widens not only in the crystal orientation

[0001] or crystal orientation

[0010] , but also when the laser beam LB is irradiated in a region along a direction in which the angle with respect to these crystal orientations is 5° or less.

[0115] Therefore, in the laser beam irradiation step (S121) of the present invention, the laser beam LB may be irradiated to a region in a plan view that is tilted by 5° or less from the crystal orientation

[0001] or the crystal orientation

[0010] .

[0116] In other words, in the laser beam irradiation step (S121) of the present invention, the crystal planes included in the crystal plane {100} are parallel to the crystal planes (here, crystal plane (100)) that are exposed on the front surface 11a and back surface 11b of the ingot 11, and the crystal orientation <100> The laser beam LB may be irradiated onto a region along a direction (first direction) where the angle it makes with a specific crystal orientation (here, crystal orientation

[0001] or crystal orientation

[0010] ) is 5° or less.

[0117] Furthermore, in the laser beam irradiation step of the present invention, the focal point where the laser beam LB is focused may be positioned at a depth shallower than the first depth, and the focal point and the ingot 11 may be moved relative to each other.

[0118] Furthermore, the separation step (S2) of the present invention may be carried out using an apparatus other than the separation apparatus 18 shown in Figures 12(A) and 12(B). For example, in the separation step (S2) of the present invention, the substrate 17 may be separated from the ingot 11 by suction on the surface 11a side of the ingot 11.

[0119] Figures 14(A) and 14(B) are schematic cross-sectional side views illustrating the separation step (S2) performed in this manner. The separation apparatus 30 shown in Figures 14(A) and 14(B) has a holding table 32 for holding the ingot 11 on which the peeled layer 15 is formed.

[0120] The holding table 32 has a circular top surface (holding surface), on which a porous plate (not shown) is exposed. Furthermore, this porous plate is in communication with a suction source (not shown), such as a vacuum pump, via a flow path or the like provided inside the holding table 32.

[0121] Therefore, when this suction source operates, an attractive force acts on the space near the holding surface of the holding table 32. This allows, for example, the holding table 32 to hold the ingot 11 placed on the holding surface.

[0122] Furthermore, a separation unit 34 is provided above the holding table 32. This separation unit 34 has a cylindrical support member 36. A ball screw type lifting mechanism (not shown), for example, is connected to the upper part of this support member 36, and the separation unit 34 moves up and down by operating this lifting mechanism.

[0123] Furthermore, the lower end of the support member 36 is fixed to the center of the upper part of the disc-shaped suction plate 38. Multiple suction ports are formed on the lower surface of the suction plate 38, and each of these ports is connected to a suction source (not shown), such as a vacuum pump, via a flow path or the like provided inside the suction plate 38.

[0124] Therefore, when this suction source operates, a suction force acts on the space near the lower surface of the suction plate 38. This allows, for example, an ingot 11 whose surface 11a is close to the lower surface of the suction plate 38 to be pulled upward by suction.

[0125] In the separation device 30, for example, the separation step (S2) is carried out in the following order. Specifically, first, the ingot 11 is placed on the holding table 32 so that the center of the back surface 11b of the ingot 11 on which the peeled layer 15 is formed coincides with the center of the holding surface of the holding table 32.

[0126] Next, a suction source communicating with a porous plate exposed on the holding surface is activated so that the ingot 11 is held by the holding table 32. Then, the lifting mechanism is activated to lower the separation unit 34 so that the lower surface of the suction plate 38 comes into contact with the surface 11a of the ingot 11.

[0127] Next, a suction source communicating with multiple suction ports is activated so that the surface 11a side of the ingot 11 is sucked through the multiple suction ports formed in the suction plate 38 (see Figure 16(A)). Then, the lifting mechanism is activated to raise the separation unit 34 so that the suction plate 38 is separated from the holding table 32 (see Figure 16(B)).

[0128] At this time, an upward force acts on the surface 11a side of the ingot 11, which is being sucked in through multiple suction ports formed in the suction plate 38. As a result, the cracks 15c contained in the release layer 15 extend further, separating the surface 11a side and the back side 11b side of the ingot 11. In other words, the substrate 17 is manufactured from the ingot 11, starting from the release layer 15.

[0129] Furthermore, in the separation step (S2) of the present invention, ultrasonic waves may be applied to the surface 11a side of the ingot 11 prior to the separation of the surface 11a side and the back surface 11b side of the ingot 11. In this case, the cracks 15c contained in the delamination layer 15 will extend further, making it easier to separate the surface 11a side and the back surface 11b side of the ingot 11.

[0130] Furthermore, in the present invention, prior to the release layer formation step (S1), the surface 11a of the ingot 11 may be planarized by grinding or polishing (planarization step). For example, this planarization may be performed when manufacturing multiple substrates from the ingot 11.

[0131] Specifically, when the ingot 11 separates in the release layer 15 to produce the substrate 17, the surface of the newly exposed ingot 11 will have irregularities that reflect the distribution of the modified portions 15a, 15b and cracks 15c contained in the release layer 15. Therefore, when producing a new substrate from this ingot 11, it is preferable to flatten the surface of the ingot 11 prior to the release layer formation step (S1).

[0132] This makes it possible to suppress diffuse reflection of the laser beam LB irradiated onto the ingot 11 in the delamination layer formation step (S1) on the surface of the ingot 11. Similarly, in the present invention, the surface of the substrate 17 separated from the ingot 11 on the side of the delamination layer 15 may be flattened by grinding or polishing.

[0133] Furthermore, the ingot used to manufacture the substrate in the present invention is not limited to the ingot 11 shown in Figures 1 and 2, etc. Specifically, in the present invention, the substrate may be manufactured from an ingot made of single-crystal silicon in which crystal planes not included in the crystal plane {100} are exposed on the front and back surfaces, respectively.

[0134] Furthermore, in the present invention, the substrate may be manufactured from a cylindrical ingot having a notch formed on its side surface. Alternatively, in the present invention, the substrate may be manufactured from a cylindrical ingot having neither an orientation flat nor a notch formed on its side surface. Furthermore, in the present invention, the substrate may be manufactured from a cylindrical ingot made of a semiconductor material other than single-crystal silicon, such as single-crystal silicon carbide.

[0135] Furthermore, in this invention, a substrate may be manufactured using a bare wafer made of a semiconductor material as the workpiece. This bare wafer has a thickness of, for example, two to five times the thickness of the substrate to be manufactured.

[0136] Furthermore, this bare wafer is manufactured, for example, by separating it from the ingot 11 using a method similar to the one described above. In this case, the substrate can also be described as being manufactured by repeating the method described above twice.

[0137] Furthermore, in the present invention, a substrate may be manufactured using a device wafer, which is produced by forming a semiconductor device on one surface of the bare wafer, as the workpiece. In this case, it is preferable that the laser beam LB is irradiated onto the device wafer from the side on which the semiconductor device is not formed, in order to prevent adverse effects on the semiconductor device.

[0138] Furthermore, the structures and methods of the embodiments described above can be modified as appropriate without departing from the scope of the present invention. [Explanation of Symbols]

[0139] 2: Laser processing equipment 4: Holding Table 6: Laser beam irradiation unit 8: Laser Oscillator 10: Attenuator 11: Ingot (11a: Front, 11b: Back, 11c: Side) 12: Branch Unit 13: Orientation Flat 14: Miller 15: Detachment layer (15a, 15b: Modified area, 15c: Crack) 16: Irradiation head 17: Circuit board 18: Separation device 20: Holding Table 22: Separation Unit 24: Support member 26: Base 28: Movable member (28a: Upright part, 28b: Wedge part) 30: Separation device 32: Holding Table 34: Separation Unit 36: Support member 38: Suction plate

Claims

1. A method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, A peel layer formation step involves irradiating the workpiece with a laser beam having a wavelength that penetrates the material constituting the workpiece from the first surface side to form a peel layer inside the workpiece that includes a modified portion and cracks extending from the modified portion. The separation step includes, after performing the peel layer formation step, separating the substrate from the workpiece using the peel layer as a starting point, The peel layer formation step is, A preliminary machining step in which the modified portion is formed in the outer peripheral region of the workpiece by positioning the focal point where the laser beam is focused in the outer peripheral region of the workpiece and moving the focal point and the workpiece relative to each other, The process includes, after performing the preliminary processing step, a laser beam irradiation step in which the focal point and the workpiece are moved relative to each of the plurality of linear regions, each extending along a first direction and with the focal point positioned in one of a plurality of linear regions contained in the workpiece, and an indexing feed step in which the position where the focal point is formed and the workpiece are moved relative to each other along a second direction perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions, The workpiece is an ingot or a bare wafer. A method for manufacturing a circuit board.

2. In the pre-processing step, the power of the laser beam is adjusted so that the crack does not extend from the modified portion. A method for manufacturing a substrate according to claim 1.

3. In the pre-processing step, the focusing point is positioned at a first depth from the first surface, In the laser beam irradiation step, the focusing point is positioned at a second depth different from the first depth from the first surface. A method for manufacturing a substrate according to claim 1 or 2.

4. The workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively. The first direction is parallel to the specific crystal plane and has an angle of 5° or less with respect to a specific crystal orientation included in crystal orientation <100>. A method for manufacturing a substrate according to claim 1 or 2.

5. The workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively. The first direction is parallel to the specific crystal plane and has an angle of 5° or less with respect to a specific crystal orientation included in crystal orientation <100>. The method for manufacturing a substrate according to claim 3.

6. A method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, A peel layer formation step involves irradiating the workpiece with a laser beam having a wavelength that penetrates the material constituting the workpiece from the first surface side to form a peel layer inside the workpiece that includes a modified portion and cracks extending from the modified portion. The separation step includes, after performing the peel layer formation step, separating the substrate from the workpiece using the peel layer as a starting point, The peel layer formation step is, A preliminary machining step in which the modified portion is formed in the outer peripheral region of the workpiece by positioning the focal point where the laser beam is focused in the outer peripheral region of the workpiece and moving the focal point and the workpiece relative to each other, The process includes, after performing the preliminary processing step, a laser beam irradiation step in which the focal point and the workpiece are moved relative to each of the plurality of linear regions, each extending along a first direction and with the focal point positioned in one of a plurality of linear regions contained in the workpiece, and an indexing feed step in which the position where the focal point is formed and the workpiece are moved relative to each other along a second direction perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions, In the pre-processing step, the power of the laser beam is adjusted so that the crack does not extend from the modified area. A method for manufacturing a circuit board.

7. In the pre-processing step, the focusing point is positioned at a first depth from the first surface, In the laser beam irradiation step, the focusing point is positioned at a second depth different from the first depth from the first surface. The method for manufacturing a substrate according to claim 6.

8. The workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively. The first direction is parallel to the specific crystal plane and has an angle of 5° or less with respect to a specific crystal orientation included in crystal orientation <100>. The method for manufacturing a substrate according to claim 6 or 7.

9. A method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, A peel layer formation step involves irradiating the workpiece with a laser beam having a wavelength that penetrates the material constituting the workpiece from the first surface side to form a peel layer inside the workpiece that includes a modified portion and cracks extending from the modified portion. The separation step includes, after performing the peel layer formation step, separating the substrate from the workpiece using the peel layer as a starting point, The peel layer formation step is, A preliminary machining step in which the modified portion is formed in the outer peripheral region of the workpiece by positioning the focal point where the laser beam is focused in the outer peripheral region of the workpiece and moving the focal point and the workpiece relative to each other, The process includes, after performing the preliminary processing step, a laser beam irradiation step in which the focal point and the workpiece are moved relative to each of the plurality of linear regions, each extending along a first direction and with the focal point positioned in one of a plurality of linear regions contained in the workpiece, and an indexing feed step in which the position where the focal point is formed and the workpiece are moved relative to each other along a second direction perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions, In the preliminary processing step, the focusing point is positioned at a first depth from the first surface. In the laser beam irradiation step, the focusing point is positioned at a second depth different from the first depth from the first surface. A method for manufacturing a circuit board.

10. The workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively. The first direction is parallel to the specific crystal plane and has an angle of 5° or less with respect to a specific crystal orientation included in crystal orientation <100>. The method for manufacturing a substrate according to claim 9.

11. A method for manufacturing a substrate from a workpiece having a first surface and a second surface opposite to the first surface, A peel layer formation step involves irradiating the workpiece with a laser beam having a wavelength that penetrates the material constituting the workpiece from the first surface side to form a peel layer inside the workpiece that includes a modified portion and cracks extending from the modified portion. The separation step includes, after performing the peel layer formation step, separating the substrate from the workpiece using the peel layer as a starting point, The peel layer formation step is, A preliminary machining step in which the modified portion is formed in the outer peripheral region of the workpiece by positioning the focal point where the laser beam is focused in the outer peripheral region of the workpiece and moving the focal point and the workpiece relative to each other, The process includes, after performing the preliminary processing step, a laser beam irradiation step in which the focal point and the workpiece are moved relative to each of the plurality of linear regions, each extending along a first direction and with the focal point positioned in one of a plurality of linear regions contained in the workpiece, and an indexing feed step in which the position where the focal point is formed and the workpiece are moved relative to each other along a second direction perpendicular to the first direction and parallel to the first surface, thereby forming the modified portion and the crack in each of the plurality of linear regions, The workpiece is made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the first plane and the second plane, respectively. The first direction is parallel to the specific crystal plane and has an angle of 5° or less with respect to a specific crystal orientation included in crystal orientation <100>. A method for manufacturing a circuit board.

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