Substrate manufacturing method

Abstract

To provide a highly productive method for manufacturing substrates. [Solution] A method for manufacturing a substrate from a cylindrical ingot includes: a detection step 1003 in which a measurement light is irradiated onto the side surface of the ingot, the ingot and the measurement light are rotated relative to each other around a rotation axis passing through the center of the ingot, and the position of a flat surface formed on the side surface of the ingot is detected based on the change in the amount of measurement light received reflected from the side surface; a release layer formation step 1004 in which a release layer is formed inside the ingot by positioning the focal point of a laser beam with a wavelength that penetrates the material constituting the ingot inside the ingot, and moving the ingot and the focal point relative to each other along a predetermined direction determined based on the position of the flat surface detected in the detection step 1003; and a release step 1005 in which the substrate is released from the ingot starting from the release layer.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a substrate.

Background Art

[0002] In the manufacturing process of a semiconductor substrate (wafer), generally, an ingot obtained by crystal growth is shaped into a cylindrical shape, and after specifying the crystal orientation by X-ray analysis, an orientation flat or notch, which is a mark indicating the crystal orientation, is formed. Then, the substrate (wafer) is obtained by thinly cutting this ingot using a wire saw (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the orientation flat and notch have a shape that cuts into the wafer diameter center direction, the area of the device region decreases, and the number of device chips that can be produced from one semiconductor substrate (wafer) decreases, resulting in a problem of poor productivity.

[0005] The present invention has been made in view of such problems, and its object is to provide a method for manufacturing a substrate with high productivity.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the present invention provides a method for manufacturing a substrate from a cylindrical ingot having a first surface, a second surface opposite to the first surface, and a side surface connected to the outer edge of the first surface and the outer edge of the second surface, comprising: a detection step in which, while irradiating the side surface of the ingot with measuring light, the ingot and the measuring light are rotated relative to each other around a rotation axis passing through the center of the ingot, and the position of a flat surface formed on the side surface of the ingot is detected based on the change in the amount of light received by the measuring light reflected from the side surface, and the ingot The method comprises a delamination layer formation step, in which a laser beam with a wavelength that penetrates the material constituting the ingot is focused at a point inside the ingot, and the ingot and the focused point are moved relative to each other along a predetermined direction to form a delamination layer inside the ingot; and a delamination step, in which, after the delamination layer formation step, the substrate is peeled off from the ingot starting from the delamination layer, wherein in the delamination layer formation step, the predetermined direction, which is the relative direction of movement between the ingot and the focused point, is determined based on the position of the flat surface detected by the detection step.

[0007] The flat surface may be formed by performing a crystal orientation measurement step, which involves measuring the crystal orientation characteristics of the ingot, and a mark formation step, which involves forming marks on the ingot indicating the crystal orientation based on the characteristics measured in the crystal orientation measurement step.

[0008] After performing the peeling step, the process may further include a shaping step in which the outer shape of the substrate peeled from the ingot is shaped and the flat surface is removed. [Effects of the Invention]

[0009] This invention involves aligning an ingot based on a flat surface formed on its side surface, which serves as a mark indicating the crystal orientation. The relative movement direction between the ingot and the focal point of the laser beam irradiated onto the ingot is determined, and a delamination layer is formed by irradiating the inside of the ingot with the laser beam. A substrate is then manufactured by delaminating the ingot starting from this delamination layer. Therefore, compared to conventional methods using orientation flats or notches, this invention can significantly suppress the amount by which the side surface of the ingot is processed radially inward. As a result, compared to conventional methods using orientation flats or notches, this invention can significantly suppress the reduction in the area of ​​the device region in the substrate manufactured from the ingot, thus greatly reducing the risk of decreased productivity due to a reduction in the number of device chips that can be produced from a single substrate. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view showing an example of an ingot used in the substrate manufacturing method according to Embodiment 1. [Figure 2] Figure 2 is a top view illustrating the ingot shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view illustrating the ingot shown in Figure 1. [Figure 4] Figure 4 is a flowchart showing the processing procedure for manufacturing a substrate according to Embodiment 1. [Figure 5] Figure 5 is a top view illustrating the crystal orientation measurement step shown in Figure 4. [Figure 6] Figure 6 is a plan view illustrating the crystal orientation measurement step shown in Figure 4. [Figure 7] Figure 7 is a perspective view illustrating a first example of the mark formation step in Figure 4. [Figure 8] Figure 8 is a perspective view illustrating a second example of the mark formation step in Figure 4. [Figure 9] Figure 9 is a perspective view illustrating the detection step shown in Figure 4. [Figure 10]FIG. 10 is a perspective view for explaining the peeling layer forming step of FIG. 4. [Figure 11] FIG. 11 is a top view for explaining the peeling layer forming step of FIG. 4. [Figure 12] FIG. 12 is a cross-sectional view for explaining the peeling step of FIG. 4. [Figure 13] FIG. 13 is a cross-sectional view for explaining the peeling step of FIG. 4. [Figure 14] FIG. 14 is a perspective view for explaining a method of manufacturing a substrate according to Embodiment 2. [Figure 15] FIG. 15 is a flowchart showing a processing procedure of a method of manufacturing a substrate according to Embodiment 2. [Figure 16] FIG. 16 is a top view for explaining the outer shape shaping step of FIG. 15. [Figure 17] FIG. 17 is a perspective view for explaining the outer shape shaping step of FIG. 15.

Mode for Carrying Out the Invention

[0011] A mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and substantially the same ones. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0012] 〔Embodiment 1〕 A method of manufacturing a substrate according to Embodiment 1 of the present invention will be described based on the drawings. FIG. 1 is a perspective view showing an example of an ingot 100 used in the method of manufacturing a substrate according to Embodiment 1. FIG. 2 is a top view for explaining the ingot 100 of FIG. 1. FIG. 3 is a cross-sectional view for explaining the ingot 100 of FIG. 1. The method of manufacturing a substrate according to Embodiment 1 is a method of manufacturing a substrate (wafer) 150 (see FIGS. 13 and 14) from an ingot 100 as shown in FIG. 1, and is a method of forming the substrate 150 by cutting the ingot 100.

[0013] As shown in FIG. 1, the ingot 100 is a columnar ingot formed as a columnar shape as a whole. The ingot 100 has a flat circular first surface 101 exposed upward, a flat circular second surface 102 exposed downward on the opposite side of the first surface 101, and is located between the first surface 101 and the second surface 102, and has a side surface 103 connecting the outer edge of the first surface 101 and the outer edge of the second surface 102. The ingot 100 is, for example, a columnar single crystal ingot made of silicon (Si), silicon carbide (SiC), gallium nitride (GaN), lithium tantalate (LT), lithium niobate (LN), gallium oxide (Ga2O3), gallium arsenide (GaAs), or other semiconductors as a constituent material.

[0014] In Embodiment 1, the ingot 100 is a hexagonal single crystal ingot made of SiC. As shown in FIGS. 1, 2, and 3, the ingot 100 is generated from a seed crystal 200 (see FIG. 14 etc.) using step-controlled epitaxial growth so that the c-axis (crystal orientation <0001>) of the single crystal SiC is slightly inclined with respect to the perpendicular 105 of the first surface 101 and the second surface 102. For example, the off-angle θ1 (see FIGS. 1 and 3), which is the angle formed by the c-axis and the perpendicular 105, is 1° to 6° (typically 4°). Also, the off-angle direction 106 (see FIGS. 1 and 3), which is orthogonal to the c-axis and in the direction in which the perpendicular 105 is inclined with respect to the c-axis, is in the direction of a predetermined crystal orientation (typically the crystal orientation <11-20>). The ingot 100 manufactured through a crystal growth process such as step-controlled epitaxial growth has a minute uneven shape on the side surface 103 as shown in FIGS. 1 and 3 before the outer shape is shaped.

[0015] In this specification, for the sake of explanation, as shown in Figures 1 and 3, the direction in which the c-axis is inclined with respect to the perpendicular 105 on the first surface 101 is defined as the inclination direction 107. The inclination direction 107 is calculated based on the off-angle θ1 and the off-angle direction 106. Furthermore, as shown in Figure 2, on the first surface 101, the direction opposite to the inclination direction 107 with respect to the position of the perpendicular 105 is defined as direction 107-2, and the two directions perpendicular to the inclination direction 107 with respect to the position of the perpendicular 105 on the first surface 101 are defined as directions 107-3 and 107-4, respectively.

[0016] Next, this specification will describe a method for manufacturing a substrate according to Embodiment 1 with reference to the drawings. Figure 4 is a flowchart showing the processing steps for manufacturing a substrate according to Embodiment 1. As shown in Figure 4, the method for manufacturing a substrate according to Embodiment 1 includes a detection step 1003, a peeling layer formation step 1004, and a peeling step 1005.

[0017] As shown in Figure 4, the substrate manufacturing method according to Embodiment 1 may further involve performing a crystal orientation measurement step 1001 and a mark formation step 1002 before performing the detection step 1003, thereby forming the flat surface 130 (see Figures 7 to 11, etc.) to be detected in the detection step 1003. Embodiment 1 describes an embodiment in which the crystal orientation measurement step 1001 and the mark formation step 1002 are performed, but the present invention is not limited thereto, and these steps may be omitted if the flat surface 130 has already been formed.

[0018] Figures 5 and 6 are a top view and a plan view illustrating the crystal orientation measurement step 1001 of Figure 4, respectively. The crystal orientation measurement step 1001 is a step in which the crystal orientation characteristics of the ingot 100 are measured, as shown in Figures 5 and 6.

[0019] In Embodiment 1, the crystal orientation measurement step 1001 can be performed using a measuring device (not shown) that includes a laser irradiator that irradiates the ingot 100 with a laser beam of a wavelength that is transparent to the ingot 100 from one side of the ingot 100, a holding table that holds the ingot 100 from the other side, an observation unit that observes the ingot 100 irradiated with the laser beam from one side, and a control unit (computer system) that controls the laser irradiator, the holding table and the observation unit and performs computer processing such as determination and calculation based on the results observed by the observation unit.

[0020] In the crystal orientation measurement step 1001, in Embodiment 1, first, a laser beam with a wavelength that is transparent to the ingot 100 is irradiated by a laser irradiator near one surface of the ingot 100 along multiple directions parallel to the horizontal plane, thereby forming linear modified layers 111, 112, 113, 114, and 115 along these multiple directions, as shown in Figure 5.

[0021] In the crystal orientation measurement step 1001, the irradiation conditions of the laser irradiator can be set to, for example, a laser beam wavelength of 1064 nm, a repetition frequency of 80 kHz, an average power of 3.2 W, a pulse width of 3 ns, a focused spot diameter of φ10 μm, a numerical aperture (NA) of the focusing lens of 0.65, a processing feed rate of 150 mm / s, and a defocus of 90 μm, thereby suitably forming the modified layers 111, 112, 113, 114, and 115.

[0022] Furthermore, in the laser beam irradiation during the crystal orientation measurement step 1001, one of the surfaces is the first surface 101 in the example shown in Figure 5, but the present invention is not limited to this and may also be the second surface 102. Also, in Embodiment 1, the multiple directions are set at predetermined angular intervals (e.g., 0.5 degrees). The modified layer is, for example, a layered region in which the density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding area.

[0023] In the laser beam irradiation during the crystal orientation measurement step 1001, specifically, the focal point of the laser beam is first positioned near the first surface 101 within the ingot 100 held by the holding table, for example, at a predetermined depth below the first surface 101 of the ingot 100. Next, a laser beam with a wavelength that is transparent to the ingot 100 is irradiated onto the ingot 100, and the focal point of the laser beam is scanned linearly to form, for example, a modified layer 111. Then, the direction in which the focal point of the laser beam is scanned is slightly changed (by predetermined angles) and the laser beam is irradiated onto the ingot 100 in the same way to sequentially form linear modified layers 112, 113, 114, and 115.

[0024] In the crystal orientation measurement step 1001, the linear modified layers 111, 112, 113, 114, and 115 formed in this manner are thought to have crack regions 121 formed on both sides of the modified layers 111, 112, 113, 114, and 115, where cracks extend along the c-planes (crystal planes (0001)) of the ingot 100, as shown in Figures 6(a), (b), (c), (d), and (e). Nodes 122 of the crack regions 121 are thought to be formed at positions spanning multiple c-planes.

[0025] Therefore, in the crystal orientation measurement step 1001, as shown in Figure 6 in Embodiment 1, the observation unit observes the previously formed linear modified layers 111, 112, 113, 114, and 115. In the crystal orientation measurement step 1001, the control unit then measures the crystal orientation characteristics of the ingot 100 based on the number of nodes 122 observed per predetermined length (e.g., 10 mm) of the modified layers 111, 112, 113, 114, and 115. In the crystal orientation measurement step 1001, as the number of observed nodes 122 decreases, it is determined that the direction in which the focal point was scanned when the modified layer was formed is close to parallel to the c-plane (the angle formed with the c-plane is small).

[0026] In the crystal orientation measurement step 1001, specifically, as shown in Figure 6(d), when the number of observed nodes 122 is 0, it is determined that the direction in which the focal point was scanned is parallel to the c-plane when the modified layer 114 is formed. Also, as shown in Figures 6(c) and (e), when the number of observed nodes 122 is relatively small (3 locations per predetermined length in the examples shown in Figures 6(c) and (e)), it is determined that the direction in which the focal point was scanned is close to parallel to the c-plane when the modified layers 113 and 115 are formed. Furthermore, in the crystal orientation measurement step 1001, as shown in Figures 6(a) and (b), when the number of observed nodes 122 is relatively large (5 locations per predetermined length in the examples shown in Figures 6(a) and (b)), it is determined that the direction in which the focal point was scanned is far from parallel to the c-plane (the angle formed with the c-plane is large).

[0027] In the crystal orientation measurement step 1001, if a modified layer 114 with zero observed nodes 122 is not obtained, two modified layers 113 and 115 with a relatively small number of observed nodes 122 are selected, and the direction between the elongation directions of the two modified layers 113 and 115 is determined to be parallel to the c-plane.

[0028] In the crystal orientation measurement step 1001, the control unit obtains the direction parallel to the c-plane on the first face 101 in this manner. Here, the direction parallel to the c-plane on the first face 101 is the direction perpendicular to the off-angle direction 106. Therefore, in the crystal orientation measurement step 1001, the control unit calculates and obtains the off-angle direction 106 based on the obtained direction parallel to the c-plane on the first face 101 and the predetermined off-angle θ1. Then, in the crystal orientation measurement step 1001, the control unit calculates and obtains the inclination direction 107 based on the off-angle direction 106 and the predetermined off-angle θ1. Note that the direction parallel to the c-plane on the first face 101, the off-angle direction 106, and the inclination direction 107 are all examples of characteristics related to the crystal orientation of the ingot 100 according to the present invention. Alternatively, one of the directions 107-2, 107-3, or 107-4 may be calculated and obtained in conjunction with or instead of the inclination direction 107.

[0029] In the crystal orientation measurement step 1001, in Embodiment 1, the crystal orientation of the ingot 100 is measured by observing the number of nodes 122 in the linear modified layers 111, 112, 113, 114, and 115 formed by irradiating the ingot 100 with a laser beam of a wavelength that is transparent to the ingot 100 along multiple directions. Therefore, compared to known methods such as X-ray diffraction, the crystal orientation measurement step 1001 of Embodiment 1 does not require large and expensive measuring equipment, thus suppressing the risk of a decrease in the productivity of the substrate 150 (see Figures 13 and 14). Note that the crystal orientation measurement step 1001 is not limited to this in the present invention, and the crystal orientation of the ingot 100 may also be measured by known methods such as X-ray diffraction.

[0030] Figures 7 and 8 are perspective views illustrating the first and second examples of the mark formation step 1002 in Figure 4, respectively. The mark formation step 1002 is a step in which marks indicating the crystal orientation are formed on the ingot 100 based on the properties measured in the crystal orientation measurement step 1001, as shown in Figures 7 and 8.

[0031] In the mark formation step 1002, specifically, the position and region for forming the flat surface 130 on the side surface 103 of the ingot 100 are first determined based on the inclination directions 107, 107-2, 107-3, and 107-4 measured in the crystal orientation measurement step 1001. In the mark formation step 1002, in the example of Embodiment 1 shown in Figures 7 and 8, it is determined that a flat surface 130 perpendicular to direction 107-3 is formed on the side surface 103 of the ingot 100 in a region extending along the direction of the perpendicular 105, which is in direction 107-3 with respect to the perpendicular 105. In addition, the present invention is not limited to mark formation step 1002. On the side surface 103 of the ingot 100, flat surfaces 130 perpendicular to the inclination direction 107, direction 107-2, and direction 107-4 may be formed in regions extending along the direction of the perpendicular 105 that are in any of the inclination directions 107, 107-2, or 107-4 with respect to the perpendicular 105. Alternatively, flat surfaces 130 may be formed in two or more of the four regions described above on the side surface 103 of the ingot 100.

[0032] In the mark formation step 1002, the position and region on the side surface 103 of the ingot 100, which was determined earlier, are then processed into a flat surface perpendicular to direction 107-3 by the mark formation device 10 (cutting device 10-1, laser processing device 10-2) which forms marks indicating the crystal orientation on the ingot 100, thereby forming the flat surface 130. Since the flat surface 130 thus formed is based on the characteristics of the crystal orientation of the ingot 100, it corresponds to the mark indicating the crystal orientation of the ingot 100 in this invention.

[0033] In the mark formation step 1002, a flat surface 130 is formed on the side surface 103 of the ingot 100 in a region that is in direction 107-3 or direction 107-4 with respect to the perpendicular 105, thereby forming a flat surface 130 in the direction of the crystal orientation <1-100> from the center. This flat surface 130 formed in this way is also formed in the direction of the crystal orientation <1-100> from the center in the substrate 150 (see Figures 13 and 14) obtained by subsequently performing the peeling step 1005.

[0034] Furthermore, in the mark formation step 1002, a flat surface 130 is formed on the side surface 103 of the ingot 100 in a region that is in a direction 107 or 107-2 with respect to the perpendicular 105, thereby forming a flat surface 130 in the direction of the crystal orientation <11-20> from the center. This flat surface 130 formed in this way will also be formed in the direction of the crystal orientation <11-20> from the center in the substrate 150 obtained by subsequently performing the peeling step 1005.

[0035] In the mark formation step 1002, the flat surface 130 may be formed in any direction on the side surface 103 of the ingot 100, but as in Embodiment 1, it is preferable to form the flat surface 130 in the direction of the crystal orientation <1-100> or crystal orientation <11-20> from the center, based on a specific off-angle direction 106. By forming the flat surface 130 in this way, the formed flat surface 130 can be made to appear as being formed in the direction of the crystal orientation <1-100> or crystal orientation <11-20> from the center in the substrate 150 obtained by subsequently performing the peeling step 1005.

[0036] In the mark formation step 1002, in the first example, as shown in Figure 7, a cutting device 10-1 including a cutting blade 11 and a spindle 12 is used to form a flat surface 130. The cutting blade 11 is mounted on the tip of the spindle 12 and rotated by the spindle 12, which acts as the axis of rotation, to cut the side surface 103 of the ingot 100 and form a flat surface 130.

[0037] The cutting blade 11 is a cutting wheel having an annular cutting edge formed to a predetermined thickness greater than the width 131 of the flat surface 130 to be formed, with abrasive grains such as diamond or CBN (Cubic Boron Nitride) fixed with a bonding agent (binder) such as metal or resin. The cutting blade 11 may be a hubless blade or a hub blade in which an annular cutting edge is fixed to the outer circumference of an annular base. In Embodiment 1, the cutting edge of the cutting blade 11 is formed to be flat on its circumferential surface. Here, "the cutting edge of the cutting blade 11 is formed to be flat" means that the shape of the cross-section of the cutting edge along the radial direction of the cutting edge is rectangular in the entire circumferential direction of the cutting edge, that is, the outer peripheral end face is flat and the edge is formed to be close to a right angle.

[0038] In the mark formation step 1002, in the first example, as shown in Figure 7, the cutting blade 11, which is rotated by the spindle 12, is driven to a predetermined cutting depth at a predetermined location within a predetermined area on the side surface 103 of the ingot 100, and the cutting blade 11 and the ingot 100 are moved relative to each other along the direction of the perpendicular 105. In this way, the rotating cutting blade 11 cuts the side surface 103 of the ingot 100 into a flat surface perpendicular to direction 107-3, following the outer peripheral end face of the cutting edge of the cutting blade 11, which has a flat processed surface, thereby forming a flat surface 130.

[0039] In the mark formation step 1002, in the second example, as shown in Figure 8, a laser processing apparatus 10-2 is used to perform so-called ablation processing, which involves irradiating the ingot 100 with a laser beam 15 of an absorbent wavelength to sublimate or evaporate the ingot 100, thereby forming a flat surface 130.

[0040] In the mark formation step 1002, in the second example, as shown in Figure 8, the laser processing device 10-2 irradiates the side surface 103 of the ingot 100 with a laser beam 15, and the irradiation position of the laser beam 15 is scanned within a predetermined area on the side surface 103 of the ingot 100, and the area is ablated to form a flat surface perpendicular to direction 107-3, thereby forming a flat surface 130. Depending on the width 131 of the flat surface 130 to be formed, the focusing spot diameter of the laser beam 15 and the intensity distribution of the laser beam 15 in the direction of the width 131 of the flat surface 130 may be adjusted, and the irradiation position of the laser beam 15 may be scanned linearly along the direction of the perpendicular 105 to form a flat surface 130.

[0041] In the mark formation step 1002, in the example of Embodiment 1 shown in Figures 7 and 8, a flat surface 130 is formed from the first surface 101 side of the ingot 100 toward the second surface 102 side. However, the present invention is not limited to this, and the flat surface 130 may be formed from the second surface 102 side of the ingot 100 toward the first surface 101 side, or the flat surface 130 may be formed between the first surface 101 and the second surface 102 of the ingot 100.

[0042] Furthermore, in the mark formation step 1002, in Embodiment 1, the flat surface 130 is formed by cutting using the cutting device 10-1 shown in Figure 7, or by ablation using the laser processing device 10-2 shown in Figure 8. However, the present invention is not limited to these, and the flat surface 130 may also be formed by grinding using a grinding wheel of a grinding device, or by polishing using a polishing pad of a polishing device.

[0043] In the marking step 1002, for example, if the outer diameter of the ingot 100 is approximately φ200 mm, the side surface 103 of the ingot 100 is machined radially inward by approximately 0.3 mm to form a flat surface 130 with a width 131 of approximately 22 mm. On the other hand, conventionally, for example, in the case of an ingot of the same size, an orientation flat (orifura) is formed by machining the side surface of the ingot radially inward by approximately 2 to 3 mm, and a notch is formed by machining the side surface of the ingot radially inward by approximately 1.5 mm. Therefore, the embodiment 1 for forming the flat surface 130 can significantly reduce the amount of machining required radially inward on the side surface 103 of the ingot 100 compared to conventional methods for forming orientation flats and notches. As a result, Embodiment 1, which forms a flat surface 130, can significantly suppress the reduction in the area of ​​the device region on the substrate 150 (see Figures 13 and 14) manufactured from the ingot 100, where devices such as semiconductor devices and optical devices are formed, compared to the case of forming conventional orientation flats or notches. Therefore, the risk of reduced productivity due to a decrease in the number of device chips that can be produced from a single substrate 150 can be significantly suppressed.

[0044] The flat surface 130 formed in the mark formation step 1002 indicates a predetermined crystal orientation of the ingot 100. Therefore, the flat surface 130 can be used as a marker to identify the crystal orientation of the ingot 100 by detecting it by irradiating it with light and receiving the reflected light in the detection step 1003 described later. Furthermore, the flat surface 130 continues to have the same properties in the substrate 150 obtained by performing the peeling step 1005. Because of these properties, the flat surface 130 is also called an orientation mirror (Orimira (registered trademark No. 4984358 of DISCO Corporation)).

[0045] Figure 9 is a perspective view illustrating the detection step 1003 in Figure 4. As shown in Figure 9, the detection step 1003 involves irradiating the side surface 103 of the ingot 100 with a measuring light 28, rotating the ingot 100 and the measuring light 28 relative to each other around a rotation axis passing through the center of the ingot 100, and detecting the position of the flat surface 130 formed on the side surface 103 of the ingot 100 based on the change in the amount of light received by the measuring light 29 reflected from the side surface 103. In the detection step 1003, the position of the flat surface 130 formed on the side surface 103 of the ingot 100 in the radial direction of the ingot 100 is detected.

[0046] The position of the flat surface 130 detected in detection step 1003 is used in the next peel layer formation step 1004. For this reason, it is preferable to perform detection step 1003 with the ingot 100 held on the holding table 32 (see Figure 10) of the laser processing apparatus 30 (see Figure 10) that performs the peel layer formation step 1004. In this case, the position of the flat surface 130 detected in detection step 1003 can be suitably used in the next peel layer formation step 1004. In the detection step 1003, in Embodiment 1, the position of the flat surface 130 is detected with respect to the ingot 100, which is held on the holding table 32 from the other side (second side 102) and has one side (first side 101) facing upwards.

[0047] In the detection step 1003, as shown in Figure 9 in Embodiment 1, the position of the flat surface 130 formed in the mark formation step 1002 is detected using the detection device 20. The detection device 20 includes a light-emitting unit 21, a light-receiving unit 22, a rotating mechanism 23, and a control unit (computer system) (not shown) that controls the light-emitting unit 21, the light-receiving unit 22, and the rotating mechanism 23.

[0048] The light-emitting unit 21 irradiates measurement light 28 toward the side surface 103 of the ingot 100 or a flat surface 130 formed on the side surface 103. The light-receiving unit 22 receives the measurement light 29 that has been reflected from the side surface 103 of the ingot 100 or the flat surface 130 formed on the side surface 103 by the light-emitting unit 21. The light-emitting unit 21 and the light-receiving unit 22 are provided adjacent to each other so that their optical axis directions are the same.

[0049] If a region on the side surface 103 of the ingot 100 where a flat surface 130 is not formed is located in the direction of the optical axis of the light-emitting unit 21 and the light-receiving unit 22, the measurement light 28 irradiated from the light-emitting unit 21 is scattered in various directions due to the minute unevenness of the side surface 103, so the light-receiving unit 22 receives measurement light 29 with a very small amount of light received compared to the irradiation amount of measurement light 28. On the other hand, as shown in Figure 9, if a flat surface 130 formed on the side surface 103 of the ingot 100 is located in the direction of the optical axis of the light-emitting unit 21 and the light-receiving unit 22, the measurement light 28 irradiated from the light-emitting unit 21 is almost completely reflected by the flat surface 130, so the light-receiving unit 22 receives measurement light 29 with a large amount of light received that is almost the same as the irradiation amount of measurement light 28.

[0050] The rotating mechanism 23 rotates the ingot 100 relative to the light-emitting unit 21 and the light-receiving unit 22 around a perpendicular line 105, which is a rotation axis passing through the center of the ingot 100. The rotating mechanism 23 is, for example, a motor and is connected to a motor driver that supplies power to drive the motor. The motor driver includes an encoder that reads the rotational position of the motor and detects the rotational speed of the motor based on the time change of the rotational position of the motor read by the encoder. The motor driver controls the rotational speed of the motor to be detected by controlling the power supplied to drive the motor. The motor driver is electrically connected to the control unit of the detection device 20 in a communicationable manner and is controlled by the control unit, which outputs the rotational position and rotational speed of the motor to the control unit of the detection device 20.

[0051] In Embodiment 1, the detection device 20 that performs the detection step 1003 may further have a height adjustment mechanism that can adjust the relative height of a holding table 32 (see Figure 10) that holds the ingot 100, and a light-emitting unit 21 that emits measurement light 28 and a light-receiving unit 22 that receives measurement light 29. In the detection step 1003, the height adjustment mechanism can be used to change the height of the ingot 100 in the direction of the perpendicular 105 for detecting the position of the flat surface 130. In the detection step 1003, the height adjustment mechanism may be used to detect the position of the flat surface 130 at one desired height in the direction of the perpendicular 105 of the ingot 100, or at multiple heights.

[0052] Furthermore, the height adjustment mechanism performs a particularly favorable function when the thickness of the ingot 100 has decreased due to repeated separation of the substrate 150 (see Figures 13 and 14). In the detection step 1003, the height adjustment mechanism changes the height of the ingot 100 in the direction of the perpendicular 105 according to the thickness of the ingot 100, thereby enabling the precise determination of the processing direction (predetermined direction 141) by performing alignment each time in the direction determination step of the subsequent delamination layer formation step 1004. The thickness of the ingot 100 is the length of the ingot 100 in the direction of the perpendicular 105, and corresponds to the distance between the first surface 101 and the second surface 102.

[0053] The control unit of the detection device 20 acquires information on the orientation of the ingot 100 rotated by the rotating mechanism 23 based on the rotation position of the motor obtained from the motor driver of the rotating mechanism 23. This allows the control unit of the detection device 20 to acquire information on the region of the side surface 103 of the ingot 100 located in the optical axis direction of the light-emitting unit 21 and the light-receiving unit 22.

[0054] In detection step 1003, in Embodiment 1, as shown in Figure 9, the detection device 20 rotates the ingot 100 around a perpendicular line 105 using a rotation mechanism 23, while irradiating it with measurement light 28 using a light-emitting unit 21 and receiving the measurement light 29 using a light-receiving unit 22. Here, the perpendicular line 105 of the ingot 100 corresponds to the axis of rotation passing through the center of the ingot 100 in this invention. As a result, the detection device 20 acquires information on the time change in the amount of measurement light 29 received by the light-receiving unit 22, and information on the time change in the region on the side surface 103 of the ingot 100 located in the optical axis direction of the light-emitting unit 21 and the light-receiving unit 22. In this time change information, the change in the amount of measurement light 29 received by the light-receiving unit 22 and the change in the region on the side surface 103 of the ingot 100 located in the optical axis direction of the light-emitting unit 21 and the light-receiving unit 22 are compared with each other through the time information.

[0055] In detection step 1003, the detection device 20 detects, based on the change in the amount of measurement light 29 received by the light receiving unit 22, the region on the side surface 103 of the ingot 100 that is located in the optical axis direction of the light emitting unit 21 and the light receiving unit 22, corresponding to when the amount of measurement light 29 received is at its maximum, as the position of the flat surface 130 formed on the side surface 103 of the ingot 100.

[0056] In Embodiment 1, the detection step 1003 may further include a first detection step of roughly measuring the position of the flat surface 130 around the entire circumference of the side surface 103 of the ingot 100 at a predetermined height, and a second detection step of more precisely measuring the position of the flat surface 130 by measuring more precisely around the region on the side surface 103 of the ingot 100 where the amount of light received by the measurement light 29 is significantly large and at its maximum. In this case, the position of the flat surface 130 can be detected more precisely.

[0057] Figures 10 and 11 are a perspective view and a top view illustrating the delamination layer formation step 1004 of Figure 4, respectively. In Embodiment 1, the delamination layer formation step 1004 includes a direction determination step, a laser beam irradiation step, and an indexing feed step. The delamination layer formation step 1004 involves performing the direction determination step to determine a predetermined direction 141, and then alternately performing the laser beam irradiation step and the indexing feed step to form a delamination layer 140 inside the ingot 100, which includes a plurality of modified layers 142 extending along the predetermined direction 141 in a plane parallel to the first surface 101, and cracks extending from the modified layers 142.

[0058] In the delamination layer formation step 1004, in Embodiment 1, as shown in Figure 10, a delamination layer 140 is formed inside the ingot 100 using a laser processing apparatus 30. The laser processing apparatus 30 includes a laser irradiator 31 that irradiates the ingot 100 with a laser beam 38 of a wavelength that penetrates the material constituting the ingot 100 from one side of the ingot 100 (first side 101), a holding table 32 that holds the ingot 100 from the other side (second side 102), a moving unit 33 that moves the laser irradiator 31 and the holding table 32 relative to each other, and a control unit (computer system) (not shown) that controls the laser irradiator 31 and the holding table 32.

[0059] The direction determination step is a step in which, in the peel layer formation step 1004, a predetermined direction 141 is determined, which is the relative direction of movement between the ingot 100 and the focal point 39 of the laser beam 38, based on the position of the flat surface 130 detected in the detection step 1003.

[0060] Here, if the constituent material of the ingot 100 is single-crystal SiC, it is preferable that this predetermined direction 141 is perpendicular to the off-angle direction 106 and parallel to one face of the ingot 100 (first face 101). When the predetermined direction 141 is set in this way, cracks extend from the linear modified layer 142 formed in the laser beam irradiation step of the delamination layer formation step 1004 along a direction perpendicular to the predetermined direction 141, so that the modified layers 142 formed parallel to and adjacent to each other tend to connect with each other due to the extending cracks. As a result, a delamination layer 140 that can be suitably peeled off in the subsequent delamination step 1005 can be suitably formed.

[0061] Therefore, in the direction determination step, the off-angle direction 106 is obtained based on the position of the flat surface 130 detected in the detection step 1003, and a predetermined direction 141 is determined based on the obtained off-angle direction 106, which is perpendicular to the off-angle direction 106 and parallel to one face (first face 101) of the ingot 100. In the direction determination step, alignment is performed to align the ingot 100 with the focal point 39 of the laser beam 38 irradiated by the laser irradiator 31 in the laser beam irradiation step, based on the position of the flat surface 130 detected in the detection step 1003, and the laser processing device 30 is set up so that the ingot 100 and the focal point 39 can be moved relative to each other along the predetermined direction 141 in the laser beam irradiation step.

[0062] As shown in Figures 10 and 11, the laser beam irradiation step involves positioning the focal point 39 of a laser beam 38 with a wavelength that penetrates the material constituting the ingot 100 inside the ingot 100, and moving the ingot 100 and the focal point 39 relative to each other along a predetermined direction 141 determined based on the position of the flat surface 130 detected by the detection step 1003, thereby forming a single modified layer 142 extending along the predetermined direction 141 and a crack extending from the modified layer 142.

[0063] In the laser beam irradiation step, first, the focal point 39 of the laser beam 38 irradiated by the laser irradiator 31 is positioned at a depth 145 (see Figure 12) corresponding to the thickness 155 (see Figure 13) of the substrate 150 (see Figures 13 and 14) manufactured from the first surface 101 of the ingot 100. Then, as shown in Figure 10, while irradiating the ingot 100 with the laser beam 38 with its focal point 39 positioned at this depth 145, the moving unit 33 moves the holding table 32 that holds the ingot 100 and the laser irradiator 31 that irradiates the laser beam 38 relatively along a predetermined direction 141. This creates a linear modified layer 142 parallel to the first surface 101 and the predetermined direction 141, as well as cracks extending from the modified layer 142 along a direction perpendicular to the predetermined direction 141, at a depth 145 from the first surface 101 inside the ingot 100.

[0064] The indexing and feeding step involves using a moving unit 33 to move the holding table 32 that holds the ingot 100 and the laser irradiator 31 that irradiates the laser beam 38 relatively by a predetermined amount 143 along a direction parallel to the first surface 101 of the ingot 100 and perpendicular to a predetermined direction 141. This step shifts the position in which one modified layer 142 is formed in the laser beam irradiation step by a predetermined amount 143. Here, the predetermined amount 143 is, for example, about twice the average length of cracks extending from a linear modified layer 142, specifically about 100 μm. By setting the predetermined amount 143 to such a length, cracks extending from two adjacent modified layers 142 formed with a predetermined amount 143 between them can connect to each other.

[0065] In the delamination layer formation step 1004, after performing the direction determination step to determine a predetermined direction 141, the laser beam irradiation step and the indexing feed step are performed alternately to form multiple linear modified layers 142 parallel to the predetermined direction 141, arranged at predetermined intervals 143, across the entire plane from the first surface 101 to a depth 145 inside the ingot 100, as shown in Figure 11. The multiple linear modified layers 142 thus formed are connected across the entire plane from the first surface 101 to a depth 145 inside the ingot 100 by cracks extending from adjacent modified layers 142 connecting with each other, forming a delamination layer 140. By applying a predetermined external force to the ingot 100, the substrate 150 with a thickness 155 (see Figure 13) corresponding to a depth 145 (see Figure 12) including the first surface 101 can be peeled off, starting from the delamination layer 140 formed in the delamination layer formation step 1004.

[0066] Figures 12 and 13 are cross-sectional views illustrating the peeling step 1005 in Figure 4. The peeling step 1005 is a step in which, after the peeling layer formation step 1004, the substrate 150 is peeled from the ingot 100, starting from the peeling layer 140 formed in the peeling layer formation step 1004, as shown in Figures 12 and 13.

[0067] The peeling step 1005 is carried out by the peeling apparatus 40 shown in Figures 12 and 13. The peeling apparatus 40 includes a holding table 41 for holding the ingot 100, a peeling unit 42, and a control unit (computer system) (not shown) for controlling the holding table 41 and the peeling unit 42, as shown in Figures 12 and 13.

[0068] The peeling unit 42 comprises a suction holding part 43 and a moving unit 44. The suction holding part 43 is formed in a disc shape and holds the first surface 101 of the ingot 100 by suction on its lower surface. The moving unit 44 moves the holding table 41 and the suction holding part 43 relative to each other, for example, along the Z-axis direction. The moving unit 44 can apply a pulling force to the ingot 100 along the Z-axis direction by applying power to the suction holding part 43, which is holding the first surface 101 of the ingot 100 held on the holding table 41, in a direction that moves them apart relative to the holding table 41 along the Z-axis direction.

[0069] In the peeling step 1005, as shown in Figures 12 and 13, first, the holding table 41 holds the ingot 100 from the second surface 102 side with the first surface 101 side exposed, and the suction holding part 43 of the peeling unit 42 holds the first surface 101 of the ingot 100 by suction. Then, the moving unit 44 of the peeling unit 42 applies a pulling force along the Z-axis direction to the ingot 100 held on the holding table 41, thereby peeling the substrate 150 with a thickness of 155, including the first surface 101, from the ingot 100 at the peeling surface 156, starting from the peeling layer 140.

[0070] In the substrate manufacturing method according to Embodiment 1, the steps of applying external force, such as inserting a wedge or applying ultrasonic waves, may be performed after the release layer formation step 1004 and before the release step 1005, or simultaneously with the release step 1005.

[0071] In the external force application step, for example, by driving a wedge into the side surface 103 of the ingot 100 at the height of the delamination layer 140, the crack in the delamination layer 140 can be further extended in a direction parallel to the first surface 101. The wedge may be driven into one location, or it may be driven into multiple locations along the circumferential direction of the ingot 100.

[0072] In the external force application step, instead of driving in a wedge, the cracks in the delamination layer 140 can also be further extended along a direction parallel to the first surface 101 by applying ultrasonic waves (elastic vibration waves in a frequency band exceeding 20 kHz) to the ingot 100. In this case, in the external force application step, ultrasonic waves are applied to the first surface 101 side via a liquid such as pure water before the first surface 101 of the ingot 100 is adsorbed and held by the lower surface of the adsorption holding part 43. Specifically, in the external force application step, the liquid to which ultrasonic waves have been applied may be sprayed toward the first surface 101 of the ingot 100, or ultrasonic waves may be applied to the first surface 101 side of the ingot 100 from an ultrasonic horn via a liquid. Furthermore, in the external force application step, on the first surface 101 side of the ingot 100, ultrasonic waves are first applied to a localized area with a diameter of approximately 5 mm to 50 mm, and then the area to which the ultrasonic waves are applied is gradually expanded, which more preferably allows the cracks in the delamination layer 140 to extend further along a direction parallel to the first surface 101.

[0073] By performing the external force application step, cracks further connect between adjacent modified layers 142, and the mechanical strength of the delamination layer 140 becomes even weaker than that of the ingot 100 outside the delamination layer 140. Therefore, the substrate 150 can be peeled from the ingot 100 with less force than when the external force application step is not performed.

[0074] In the substrate manufacturing method according to Embodiment 1, a substrate 150 with a thickness of 155 is manufactured by sequentially performing the following steps on an ingot 100: crystal orientation measurement step 1001, mark formation step 1002, detection step 1003, delamination layer formation step 1004, and delamination step 1005.

[0075] The substrate 150 manufactured in this way has a portion corresponding to the flat surface 130 formed on the ingot 100 that can be used as a marker to identify the crystal orientation of the substrate 150. The substrate 150 manufactured in this way can be processed into a device substrate such as a semiconductor device substrate or an optical device substrate by, for example, grinding the peeled surface 156 to make it flat, forming a grid of multiple division lines on one surface, and forming devices such as semiconductor devices or optical devices in the regions demarcated by the multiple division lines.

[0076] The substrate manufacturing method according to Embodiment 1, having the above configuration, involves aligning the ingot 100 based on a flat surface 130 formed on the side surface 103 of the ingot 100, which serves as a mark indicating the crystal orientation; determining a predetermined direction 141, which is the relative movement direction between the ingot 100 and the focal point 39 of the laser beam 38 irradiated onto the ingot 100; irradiating the inside of the ingot 100 with the laser beam 38 to form a peel layer 140; and manufacturing the substrate 150 by peeling the ingot 100 starting from this peel layer 140. In this way, the substrate manufacturing method according to Embodiment 1 involves using the flat surface 130, which serves as a mark indicating the crystal orientation, to process the ingot 100 based on the crystal orientation and manufacture the substrate 150.

[0077] Therefore, the substrate manufacturing method according to Embodiment 1 can significantly suppress the amount by which the side surface 103 of the ingot 100 is processed radially inward, compared to the conventional method using orientation flats or notches. As a result, the substrate manufacturing method according to Embodiment 1 can significantly suppress the reduction in the area of ​​the device region on the substrate 150 manufactured from the ingot 100, compared to the conventional method using orientation flats or notches. This has the effect of significantly suppressing the risk of reduced productivity due to a decrease in the number of device chips that can be produced from a single substrate 150.

[0078] Furthermore, the substrate manufacturing method according to Embodiment 1 further includes a crystal orientation measurement step 1001 for measuring the characteristics of the crystal orientation of the ingot 100 before performing the detection step 1003, and a mark formation step 1002 for forming a flat surface 130, which is a mark indicating the crystal orientation of the ingot 100, on the side surface 103 of the ingot 100 based on the characteristics measured in the crystal orientation measurement step 1001. Therefore, the substrate manufacturing method according to Embodiment 1 can more preferably achieve effects such as greatly suppressing the amount by which the side surface 103 of the ingot 100 is processed radially inward.

[0079] [Embodiment 2] A method for manufacturing a substrate according to Embodiment 2 of the present invention will be described based on the drawings. Figure 14 is a perspective view illustrating the method for manufacturing a substrate according to Embodiment 2. Figure 15 is a flowchart showing the processing steps for manufacturing a substrate according to Embodiment 2. Figures 16 and 17 are a top view and a perspective view illustrating the outline shaping step 1006 of Figure 15, respectively. Note that the same reference numerals are used for the same parts as in Embodiment 1 in Figures 14 to 17, and their descriptions are omitted.

[0080] In Embodiment 1, as shown on the right side of Figure 14, a crystal orientation measurement step 1001 and a mark formation step 1002 are performed on an ingot 100 generated from a seed crystal 200 to measure the characteristics related to the crystal orientation and form a flat surface 130. Then, a detection step 1003, a delamination layer formation step 1004, and a delamination step 1005 are performed to detect the formed flat surface 130, determine the processing orientation, form a delamination layer 140, and delaminate to manufacture a substrate 150.

[0081] In Embodiment 2, as shown on the left side of Figure 14, the same crystal orientation measurement step 1001 and mark formation step 1002 as in Embodiment 1 are performed on the seed crystal ingot 300 to measure the characteristics related to the crystal orientation and form a flat surface 130. The same detection step 1003, peel layer formation step 1004 and peel step 1005 as in Embodiment 1 are performed to detect the formed flat surface 130, determine the processing orientation, form a peel layer 140, and peel off to manufacture a seed crystal 200. Furthermore, the method of performing the external shaping step 1006, which will be described later, on the manufactured seed crystal 200 will be explained. Here, the seed crystal ingot 300 and seed crystal 200 in Embodiment 2 are examples corresponding to the ingot 100 and substrate 150 in the present invention, respectively.

[0082] The substrate manufacturing method according to Embodiment 2, as shown in Figure 15, is a modification of the substrate manufacturing method according to Embodiment 1, further including an outline shaping step 1006 after performing the peeling step 1005. The outline shaping step 1006 does not involve shaping the ingot 100 or seed crystal ingot 300 into a cylindrical shape as in the conventional method, but rather involves shaping the substrate-shaped seed crystal 200 obtained by performing each of the steps from crystal orientation measurement step 1001 to peeling step 1005 on the seed crystal ingot 300 into a disc shape.

[0083] Furthermore, since the substrate manufacturing method according to Embodiment 2 does not require the implementation of the outer shape shaping step 1006, the present invention also includes a form in which the outer shape shaping step 1006 is omitted and the seed crystal ingot 300 is subjected to the same processing as the substrate manufacturing method according to Embodiment 1.

[0084] The external shaping step 1006 is a step in which, after performing the peeling step 1005, the external shape of the seed crystal 200 peeled from the seed crystal ingot 300 is shaped into a circular external shape 210 and the flat surface 130 is removed, as shown in Figures 16 and 17.

[0085] The external shaping step 1006 is performed by the external shaping apparatus 50 shown in Figure 17. The external shaping apparatus 50, as shown in Figure 17, includes a clamping mechanism 51 that holds the seed crystal 200 between a first surface 201 and a second surface 202, a cup grinding wheel 52 that grinds the outer circumference of the seed crystal 200, a moving unit 53 that moves the clamping mechanism 51 and the cup grinding wheel 52 relative to each other, and a control unit (computer system) (not shown) that controls the clamping mechanism 51, the cup grinding wheel 52 and the moving unit 53. The clamping mechanism 51 is provided with a rotational drive source (not shown) that rotates the clamping mechanism 51 around its central axis. The cup grinding wheel 52 is provided with a rotational drive source (not shown) that rotates the cup grinding wheel 52 around its central axis.

[0086] In the outer shaping step 1006, as shown in Figure 17, first, the seed crystal 200 is held between the first surface 201 and the second surface 202 by the clamping mechanism 51, and the cup grinding wheel 52 is positioned toward the outer circumference of the seed crystal 200 held by the clamping mechanism 51 by the moving unit 53. Then, by rotating the clamping mechanism 51 around its central axis, the seed crystal 200 is rotated around the perpendicular line 205, and the cup grinding wheel 52 is pressed toward the outer circumference of the seed crystal 200 while rotating the cup grinding wheel 52 around its central axis, thereby grinding the outer circumference of the seed crystal 200 with the cup grinding wheel 52.

[0087] In the outer shaping step 1006, the cup grinding wheel 52 grinds the outer surface of the seed crystal 200 radially inward by approximately 50 μm in the region where the flat surface 130 is formed, and grinds the outer surface of the seed crystal 200 radially inward by approximately 2 to 3 mm in the region where the flat surface 130 is not formed. In this way, the outer shape of the seed crystal 200 is shaped into the circular outer shape 210 shown in Figure 16, and the flat surface 130 is removed.

[0088] The seed crystal 200, whose outer diameter has been shaped by the external shaping step 1006, is used to produce an ingot 100 through a crystal growth process, as shown in Figure 14.

[0089] The substrate manufacturing method according to Embodiment 2, having the above configuration, involves performing the same crystal orientation measurement step 1001, mark formation step 1002, detection step 1003, delamination layer formation step 1004, and delamination step 1005 as in Embodiment 1 on a seed crystal ingot 300 having the same physical properties as the ingot 100, thereby manufacturing a seed crystal 200 with the same thickness as the substrate 150. Therefore, the substrate manufacturing method according to Embodiment 2 will have the same effects as Embodiment 1.

[0090] The substrate manufacturing method according to Embodiment 2 further includes an outline shaping step 1006 in which the seed crystal 200, manufactured by peeling it off from the seed crystal ingot 300, is shaped into a circular outline 210 and the flat surface 130 is removed. Therefore, the substrate manufacturing method according to Embodiment 2 has the effect of suppressing the possibility that the flat surface 130 may affect the crystal growth for subsequent production of the ingot 100 from the seed crystal 200.

[0091] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. [Explanation of Symbols]

[0092] 28,29 Measurement light 38 Laser beams 39 Focusing points 100 ingots 101 First side 102 Second side 103 Side view 105 Perpendicular line 130 Flat surface 140 Exfoliation layer 141 predetermined direction 150 circuit boards 200 seed crystals 300 types of crystal ingots 1001 Crystal orientation determination step 1002 Mark formation step 1003 Detection Step 1004 Step to form a peeling layer 1005 Peeling step 1006 Outline shaping step

Claims

1. A method for manufacturing a substrate from a cylindrical ingot having a first surface, a second surface opposite to the first surface, and sides connected to the outer edge of the first surface and the outer edge of the second surface, A detection step in which, while irradiating the side surface of the ingot with a measuring light, the ingot and the measuring light are rotated relative to each other around a rotation axis passing through the center of the ingot, and the position of a flat surface formed on the side surface of the ingot is detected based on the change in the amount of light received by the measuring light reflected from the side surface, A delamination layer formation step involves positioning the focal point of a laser beam with a wavelength that penetrates the material constituting the ingot inside the ingot, and moving the ingot and the focal point relative to each other along a predetermined direction to form a delamination layer inside the ingot. The process includes, after the delamination layer formation step, a delamination step in which the substrate is peeled off from the ingot starting from the delamination layer, A method for manufacturing a substrate, characterized in that, in the delamination layer formation step, the predetermined direction, which is the relative direction of movement between the ingot and the focal point, is determined based on the position of the flat surface detected in the detection step.

2. The flat surface is, A crystal orientation measurement step for measuring the crystal orientation characteristics of the ingot, A marking step in which marks indicating the crystal orientation are formed on the ingot based on the properties measured in the crystal orientation measurement step, A method for manufacturing a substrate according to claim 1, characterized in that it is formed by carrying out the following.

3. A method for manufacturing a substrate according to claim 1 or 2, further comprising a shape shaping step of shaping the outer shape of the substrate peeled off from the ingot and removing the flat surface, after performing the peeling step.

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