Method for manufacturing a si substrate

Abstract

Provided is a Si substrate manufacturing method capable of efficiently manufacturing a Si substrate from a Si ingot. The Si substrate manufacturing method includes: a separation band forming step of positioning a condensing point of laser light of a wavelength that is transmissive to Si at a depth from a flat surface of the Si ingot that corresponds to the thickness of the Si substrate to be manufactured, forming a separation band while relatively moving the condensing point and the Si ingot in a direction <110> parallel to an intersection line of a crystal plane {100} and a crystal plane {111} or a direction [110] orthogonal to the intersection line, and irradiating the Si ingot with the laser light; and an indexing feed step of relatively indexing feeding the condensing point and the Si ingot in a direction orthogonal to the direction in which the separation band is formed.

Description

Technical Field

[0001] This invention relates to a method for manufacturing Si substrates by fabricating Si substrates from Si ingots. Background Technology

[0002] Multiple devices such as ICs and LSIs are formed on the upper surface of a silicon substrate by dividing it into wafers through multiple intersecting predetermined dividing lines. These wafers are then divided into individual device chips by a dicing device and a laser processing device. The divided device chips are then used in electrical devices such as mobile phones and personal computers.

[0003] Silicon (Si) substrates are formed by slicing Si crystal ingots into slices of about 1 mm thickness using a cutting device equipped with an inner circumferential blade and a wire saw, followed by grinding and polishing (see, for example, Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-94221 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, the cutting depth of the inner circumferential blade and wire saw is about 1 mm, which is relatively large. Therefore, when using the inner circumferential blade and wire saw to manufacture Si substrates from Si ingots, the amount of raw materials used as Si substrates is about 1 / 3 of the amount of Si ingots, resulting in poor productivity.

[0009] Therefore, the object of the present invention is to provide a method for manufacturing Si substrates that can efficiently manufacture Si substrates from Si ingots.

[0010] Methods for solving problems

[0011] According to the present invention, a method for manufacturing a Si substrate is provided, which is a method for manufacturing a Si substrate from a Si ingot having a flat crystal plane (100). The manufacturing method includes the following steps: a stripping strip formation step, wherein a focal point of a laser beam of wavelength that is translucent to Si is positioned at a depth from the flat surface corresponding to the thickness of the Si substrate to be manufactured, while the focal point is aligned with the Si ingot in a direction parallel to the intersection line of the crystal plane {100} and the crystal plane {111}. <110> The laser beam is irradiated onto the Si ingot in a direction or orthogonal to the cross line

[110] to form a release band; in the indexing feed process, the focus point and the Si ingot are indexed relative to each other in a direction orthogonal to the direction in which the release band is formed; and in the wafer manufacturing process, the release band forming process and the indexing feed process are repeatedly performed to form a release layer parallel to the crystal plane (100) inside the Si ingot, and the Si substrate is peeled off from the release layer of the Si ingot to manufacture a wafer.

[0012] Preferably, the focal point of the laser beam is branched into multiple points in the indexing feed direction. In this indexing feed process, it is preferable to perform the indexing feed in such a way that adjacent stripping bands contact each other. Preferably, a planarization process is further included before the stripping band formation process to planarize the crystal surface (100) of the Si ingot.

[0013] The effects of the invention

[0014] According to the present invention, Si substrates can be efficiently manufactured from Si ingots. Attached Figure Description

[0015] Figure 1 (a) is a three-dimensional view of a Si ingot. Figure 1 (b) is Figure 1 (a) is a top view of a Si ingot.

[0016] Figure 2 (a) is a 3D view of other Si ingots. Figure 2 (b) is Figure 2 (a) is a top view of a Si ingot.

[0017] Figure 3 This is a schematic diagram of a laser processing device.

[0018] Figure 4 (a) is a perspective view showing the state of the stripping belt forming process. Figure 4 (b) is a front view showing the state of the stripping belt forming process.

[0019] Figure 5 (a) is a cross-sectional view of the Si ingot with the formation of the exfoliation band. Figure 5 (b) is Figure 5Enlarged view of the stripping band in (a).

[0020] Figure 6 This is a graph showing the relationship between the number of laser beam branches and the crack length.

[0021] Figure 7 It is a graph showing the relationship between the spacing between the focal points of the branches and the crack length.

[0022] Figure 8 This is a graph showing the relationship between machining feed rate and crack length.

[0023] Figure 9 This is a graph showing the relationship between the output power of the laser beam and the crack length.

[0024] Figure 10 (a) is a perspective view showing the Si ingot positioned below the lift-off device. Figure 10 (b) is a perspective view showing the state of the stripping process being carried out using a stripping device. Figure 10 (c) is a three-dimensional view of the Si ingot and the Si substrate.

[0025] Figure 11 This is a schematic cross-sectional view showing the state of applying ultrasonic waves to a Si ingot with a release layer to perform a release process.

[0026] Figure 12 This is a perspective view showing the state of the wafer grinding process being carried out.

[0027] Figure 13 It is a three-dimensional view showing the state of the planarization process. Detailed Implementation

[0028] The preferred embodiments of the Si substrate manufacturing method of the present invention will be described below with reference to the accompanying drawings.

[0029] Figure 1 A Si (silicon) ingot 2 is shown, which is the basis for implementing the Si substrate manufacturing method of the present invention. The Si ingot 2 is integrally formed into a cylindrical shape, having a circular first end face 4 with a flat crystal plane (100), a circular second end face 6 opposite to the first end face 4, and a peripheral surface 8 located between the first end face 4 and the second end face 6. A flat rectangular orientation plane 10 is formed in the peripheral surface 8 of the Si ingot 2. The orientation plane 10 is positioned at an angle of 45° relative to the intersection line 12 of the crystal plane {110} and the crystal plane {111}.

[0030] like Figure 2 As shown, an axially extending notch 14 can also be formed in the peripheral surface 8 of the Si ingot 2 to replace the orientation plane 10. (Refer to...) Figure 2As can be understood in (b), the notch 14 is positioned such that the angle formed by the tangent 16 of the notch 14 and the intersection line 12 is 45°. It should be noted that in the following description, the method for manufacturing a Si substrate from a Si ingot 2 with an orientation plane 10 formed will be described.

[0031] In this embodiment, the first step is to perform a stripping band formation process. The focal point of a laser beam with a wavelength transparent to Si is positioned at a depth from the flat surface (first end face 4) equivalent to the thickness of the Si substrate to be manufactured. Simultaneously, the focal point and the Si ingot 2 are aligned in a direction parallel to the intersection line 12 between crystal planes {100} and {111}. <110> The laser beam is irradiated onto the Si ingot 2 in a direction

[110] that is perpendicular to the cross line 12, forming a stripping band.

[0032] The stripping band forming process can be used, for example, in... Figure 3 and Figure 4 A portion of the laser processing apparatus 18 is shown in (a) to implement the process. The laser processing apparatus 18 includes a holding stage 20 for holding the Si ingot 2 and a laser beam irradiation unit 22 for irradiating the Si ingot 2 held on the holding stage 20 with pulsed laser beams LB.

[0033] The platform 20 is configured to rotate freely about an axis extending in the vertical direction, and is configured to... Figure 3 and Figure 4 The X-axis direction indicated by the middle arrow X and the Y-axis direction orthogonal to the X-axis direction ( Figure 3 and Figure 4 The stage 20 can move freely forward and backward in the direction indicated by the middle arrow Y. Furthermore, the stage 20 is configured to move freely from the processing area of ​​the laser processing apparatus 18 to the respective processing areas of the stripping apparatus 42 and the grinding apparatus 52 (described later). It should be noted that the planes defined by the X-axis and Y-axis directions are substantially horizontal.

[0034] Reference Figure 3 To illustrate, the laser beam irradiation unit 22 includes: a laser oscillator 24 that emits pulsed laser beams LB with wavelengths that are transparent to Si; an attenuator 26 that adjusts the output power of the pulsed laser beams LB emitted from the laser oscillator 24; a spatial light modulator 28 that branches the pulsed laser beams LB, whose output power has been adjusted by the attenuator 26, into multiple (e.g., 5) branches at predetermined intervals in the Y-axis direction; a reflector 30 that reflects the pulsed laser beams LB after they have been branched by the spatial light modulator 28 to change the direction of the light path; and a concentrator 32 that focuses the pulsed laser beams LB reflected by the reflector 30 and irradiates them onto the Si ingot 2.

[0035] In the stripping band forming process, the Si ingot 2 is first fixed to the upper surface of the holding stage 20 using a suitable adhesive (e.g., an epoxy resin adhesive). Alternatively, multiple suction holes can be formed on the upper surface of the holding stage 20 to generate an attractive force to hold the Si ingot 2.

[0036] Next, the Si ingot 2 is photographed from above using the camera unit (not shown) of the laser processing apparatus 18. Based on the image of the Si ingot 2 captured by the camera unit, the holding stage 20 is rotated and moved, thereby adjusting the orientation of the Si ingot 2 to a predetermined orientation and adjusting the position of the Si ingot 2 and the condenser 32 in the XY plane. When adjusting the orientation of the Si ingot 2 to the predetermined orientation, such as... Figure 4 As shown in (a), the orientation plane 10 is adjusted so that the X-axis direction forms a 45° angle with the orientation plane 10, so that the direction is parallel to the intersection line 12 of the crystal plane {110} and the crystal plane {111}. <110> Aligned with the X-axis direction.

[0037] Next, the focusing point position adjustment mechanism (not shown) of the laser processing device 18 is used to raise and lower the focusing point FP of the pulsed laser beam LB (refer to...). Figure 4 (b) is positioned at a depth corresponding to the thickness of the Si substrate to be manufactured, from the first end face 4, which is a flat surface. In this embodiment, the pulsed laser beam LB is branched into multiple segments at predetermined intervals in the Y-axis direction by the spatial light modulator 28, but the focusing points FP of the branched pulsed laser beams LB are respectively positioned at the same depth.

[0038] Next, while keeping platform 20 in the same direction <110> Consistent X-axis direction (this direction) <110> It is parallel to the intersection of crystal plane {100} and crystal plane {111}. Figure 1 (b) and Figure 2 The laser beam moves at a predetermined feed rate along the direction of the cross line 12 shown in (b), while irradiating the Si ingot 2 with pulsed laser light LB of a wavelength that is transparent to Si from the concentrator 32. Thus, as... Figure 5 (a) and Figure 5As shown in (b), the crystal structure is destroyed near the five focal points FP of the pulsed laser beam LB, and along... <110> A crack 36 is formed in the direction (X-axis direction), and a peeling band 38 is isotropically extended from the portion 34 where the crystal structure is damaged along the (111) plane. In this embodiment, the focusing point FP and the Si ingot 2 are aligned in the direction parallel to the intersection line 12 where the crystal plane {100} and the crystal plane {111} intersect. <110> The same stripping band 38 as described above can also be formed if the focus point FP and the Si ingot 2 are moved relative to each other in a direction orthogonal to the cross line 12

[110] . It should be noted that in the stripping band formation process, the focuser 32 can be moved along the X-axis instead of the holding stage 20. In addition, in this embodiment, the pulsed laser beam LB is branched into multiple branches to irradiate the Si ingot 2, but the pulsed laser beam LB can also irradiate the Si ingot 2 without branching.

[0039] Next, an indexing feed process is performed, in which the focusing point FP and the Si ingot 2 are indexed relative to each other in a direction orthogonal to the direction in which the release band 38 is formed. In the indexing feed process of this embodiment, the holding stage 20 is positioned relative to the direction in which the release band 38 is formed. <110> Li is measured in a specified fraction along the Y-axis direction (orthogonal to the X-axis direction) (refer to...) Figure 4 (a)) Indexing feed is performed. It should be noted that, in the indexing feed process, the condenser 32 can also be indexed feed instead of the holding table 20.

[0040] Next, the wafer manufacturing process is carried out, and the stripping layer formation process and indexing feed process are repeatedly carried out to form a stripping layer that is parallel to the crystal plane (100) as a whole inside the Si ingot 2. The Si substrate is peeled off from the stripping layer of the Si ingot 2 to manufacture the wafer.

[0041] By repeatedly performing the stripping belt formation process and the indexing feed process, such as Figure 5 As shown in (a), a reduced-strength exfoliation layer 40 consisting of multiple exfoliation bands 38 can be formed inside the Si ingot 2. Cracks 36 in each exfoliation band 38 extend along the (111) plane, but refer to... Figure 5 (a) can be understood that the peeling layer 40, which consists of multiple peeling strips 38, is parallel to the first end face 4 as a whole.

[0042] A small gap may be provided between the cracks 36 of adjacent peeling bands 38, but in the indexing feed process, it is preferable to perform the indexing feed in such a way that the adjacent peeling bands 38 are in contact. As a result, the adjacent peeling bands 38 can be connected to each other, further reducing the strength of the peeling layer 40, and the Si substrate can be easily peeled from the Si ingot 2 in the peeling process described below.

[0043] The preferred processing conditions for forming such a release layer 40 are as follows. The inventors conducted experiments under various conditions and found that by forming the release band 38 under the following processing conditions, the cracks 36 in the release band 38 become longer, thus increasing the fractional mass Li and shortening the time required to form the release layer 40.

[0044] Laser beam wavelength: 1342nm

[0045] Average output power of the laser beam before branching: 2.5W

[0046] Number of branches at the focal point: 5 (based on the results of Experiment 1 below)

[0047] The spacing between the branched focusing points is 10 μm (based on the results of Experiment 2 below).

[0048] Repetition frequency: 60kHz

[0049] Feed rate: 300 mm / s (based on the results of Experiment 3 below)

[0050] Scale measure: 320 μm (based on the results of Experiment 4 below)

[0051] Reference Figures 6 to 9 The experimental results related to the formation of the release layer conducted by the inventors are explained. The inventors changed the number of branches of the pulsed laser beam, the spacing of the focal points of the branched pulsed laser beams, the relative feed speed between the Si ingot and the focal point, and the output power of the pulsed laser beam. The focal point of the pulsed laser beam with a wavelength that is transparent to Si was positioned at a depth equivalent to the thickness of the Si substrate to be manufactured from the upper end face (the upper end face where the crystal plane (100) is a flat surface). At the same time, the focal point and the Si ingot were aligned in a direction parallel to the intersection line of the crystal plane {100} and the crystal plane {111}. <110> The silicon ingot is moved relative to the silicon crystal while being irradiated with a pulsed laser beam, and the crack length of the peeling zone is measured at this time. It should be noted that in the following experiments, except for the changed parameters, the processing conditions are set according to the above processing conditions, and the description of other processing conditions is omitted.

[0052] <Experiment 1>

[0053] Figure 6 The figure shows the measurement results of the length of the crack in the Y-axis direction of the stripping zone when the average output power of each branched beam is 0.5W and the number of branches of the pulsed laser beam is varied. Figure 6 As shown, with 3, 4, and 5 branches, the more branches the pulsed laser beam has, the longer the crack becomes.

[0054] <Experiment 2>

[0055] Figure 7 The figure shows the measurement results of the length of the crack in the Y-axis direction of the stripping zone when the spacing of the focusing points of the branched pulsed laser beam is changed (● mark). Figure 7 As shown, the crack length is maximized when the spacing between the focusing points of the branched pulsed laser beam is 10 μm. Furthermore, Figure 7 In the example shown, as a comparison, the results of irradiating a Si ingot with a pulsed laser beam while moving the focal point relative to the Si ingot in a direction parallel to the orientation plane are also illustrated (× mark). See reference. Figure 7 It can be understood that the focusing point is aligned with the Si ingot in a direction parallel to the intersection line between crystal planes {100} and {111}. <110> In the case of relative movement (● mark), regardless of the spacing of the focal points of the branched pulsed laser beam, the crack length is longer than in the case where the focal points are moved relative to the Si ingot parallel to the orientation plane (× mark).

[0056] Experiment 3

[0057] Figure 8 The figure shows the measurement results of the length of the peeling zone crack in the Y-axis direction when the relative feed rate between the Si ingot and the focusing point is changed. (Refer to...) Figure 8 It is understandable that the crack length is maximized when the feed rate is 300 mm / s. It should be noted that in Experiment 3, in order to confirm the optimal feed rate, the number of branches at the focal point of the pulsed laser beam was set to 3, and the average output power of the pulsed laser beam was set to 1.8 W (the average output power of each beam after branching was 0.5 W).

[0058] Experiment 4

[0059] Figure 9 The figure shows the measurement results of the length of the crack in the stripping zone in the Y-axis direction when the average output power of the pulsed laser beam before branching is changed. Figure 9 In the diagram marked with ●, the broken line represents the branch number 5, which directs the focus point and the Si ingot along the intersection line parallel to the intersection of crystal plane {100} and crystal plane {111}. <110> The diagram shows the relative movement between the focal point and the Si ingot, with 5 branches and the focal point moving relative to the orientation plane. The diagram shows the relative movement between the focal point and the Si ingot, with 3 branches and the focal point moving in the direction parallel to the intersection of crystal planes {100} and {111}. <110> The case of relative movement.

[0060] Depend on Figure 9It can be seen that: (1) the higher the output power of the pulsed laser beam, the longer the crack; (2) the more branches, the longer the crack; (3) compared with the case where the focusing point and the Si ingot move relative to each other parallel to the orientation plane, the case where the focusing point and the Si ingot move in the direction parallel to the intersection line of the crystal plane {100} and the crystal plane {111}. <110> When there is relative movement, the crack lengthens. Additionally, refer to... Figure 9 It is understandable that, in the broken line graph marked with ●, the crack length is the largest (320 μm) when the output power is 2.5 W.

[0061] Returning to the explanation of the wafer manufacturing process, after a release layer 40 is formed inside the Si ingot 2, the Si substrate is peeled off from the release layer 40 of the Si ingot 2 to manufacture a wafer. When peeling the Si substrate off the release layer 40 of the Si ingot 2, for example, a method can be used... Figure 10 The peeling device 42 shown is used to perform this action.

[0062] like Figure 10 As shown, the peeling device 42 includes a substantially horizontally extending arm 44 and a motor 46 attached to the front end of the arm 44. A circular, plate-shaped adsorption plate 48, which rotates freely about an axis extending vertically, is connected to the lower surface of the motor 46. An ultrasonic vibration application mechanism (not shown) is built into the adsorption plate 48, which is configured to adsorb the workpiece on its lower surface.

[0063] Reference Figure 10 Continuing the explanation, after the release layer 40 is formed inside the Si ingot 2, the holding stage 20 holding the Si ingot 2 is moved downwards towards the adsorption sheet 48. Next, the arm 44 is lowered, as... Figure 10 As shown in (b), the lower surface of the adsorption sheet 48 is adsorbed onto the first end face 4 (the end face near the release layer 40) of the Si ingot 2. Next, the ultrasonic vibration application mechanism is activated to apply ultrasonic vibration to the lower surface of the adsorption sheet 48, while the motor 46 rotates the adsorption sheet 48. Thus, as... Figure 10 As shown in (c), a wafer can be manufactured by peeling the Si substrate 50 (wafer) from the Si ingot 2 starting from the peeling layer 40.

[0064] Additionally, when peeling the Si substrate 50 from the release layer 40 of the Si ingot 2, the following can be used: Figure 11 The peeling device 52 shown. Figure 11 The peeling device 52 shown includes a water tank 54, a rod 56 that is freely raised and lowered within the water tank 54, and an ultrasonic oscillation component 58 installed at the lower end of the rod 56.

[0065] When peeling the Si substrate 50 from the Si ingot 2 using the peeling device 52, the Si ingot 2 is immersed in water 60 in the water tank 54. Next, the rod 56 is moved to position the ultrasonic oscillation component 58 slightly above the first end face 4 of the Si ingot 2. The distance between the first end face 4 of the Si ingot 2 and the ultrasonic oscillation component 58 can be approximately 1 mm. Then, ultrasonic waves are emitted by the ultrasonic oscillation component 58, stimulating the peeling layer 40 through the water 60 layer, thereby enabling the Si substrate 50 to be peeled from the Si ingot 2 starting from the peeling layer 40.

[0066] After the wafer manufacturing process, a wafer grinding process is performed to planarize the Si substrate 50 by grinding the release surface 50a. The wafer grinding process can be used, for example, in... Figure 12 The grinding apparatus 62 shown is used to implement this process. The grinding apparatus 62 includes a chuck stage 64 for holding and gripping the Si substrate 50, and a grinding mechanism 66 for grinding the Si substrate 50 held and gripped by the chuck stage 64. The chuck stage 64 for holding and gripping the Si substrate 50 on its upper surface is configured to rotate freely about an axis extending in the vertical direction.

[0067] like Figure 12 As shown, the grinding mechanism 66 includes: a spindle 68 configured to rotate freely around an axis in the vertical direction, and a circular grinding wheel mounting base 70 fixed to the lower end of the spindle 68. An annular grinding wheel 74 is fixed to the lower surface of the grinding wheel mounting base 70 by bolts 72. A plurality of grinding stones 76 arranged in a ring at circumferential intervals are fixed to the outer periphery of the lower surface of the grinding wheel 74.

[0068] Reference Figure 12Continuing the explanation, in the wafer grinding process, firstly, a circular substrate 78 is mounted on the side of the Si substrate 50 opposite to the peeling surface 50a using a suitable adhesive. Next, with the peeling surface 50a of the Si substrate 50 facing upwards, the substrate 78 and the Si substrate 50 are attracted and held together on the upper surface of the chuck stage 64. Then, the chuck stage 64 is rotated counterclockwise at a predetermined speed (e.g., 300 rpm) when viewed from above. Simultaneously, the spindle 68 is rotated counterclockwise at a predetermined speed (e.g., 6000 rpm) when viewed from above. Next, the spindle 68 is lowered using the lifting mechanism (not shown) of the grinding apparatus 62, bringing the grinding stone 76 into contact with the peeling surface 50a of the Si substrate 50. After the grinding stone 76 contacts the peeling surface 50a of the Si substrate 50, the spindle 68 is lowered at a predetermined grinding feed rate (e.g., 1.0 μm / s). Therefore, the release surface 50a of the Si substrate 50 can be ground to planarize the Si substrate 50. It should be noted that after grinding the release surface 50a, a suitable grinding device can be used to grind the planarized release surface 50a until the desired surface roughness is achieved.

[0069] In addition, after the wafer manufacturing process, before or after the wafer grinding process, a planarization process is performed in parallel with the wafer grinding process to grind the stripping surface 4' of the Si ingot 2 after the Si substrate 50 is stripped, and the crystal surface (100) is planarized.

[0070] When a planarization process is performed before or after the wafer grinding process, the grinding mechanism 66 of the grinding apparatus 62 described above can be used to perform the planarization process. When performing the planarization process using the grinding mechanism 66, the chuck stage 64 is first separated from the area below the grinding mechanism 66, and then the holding stage 20 holding the Si ingot 2 is moved to the area below the grinding mechanism 66.

[0071] Next, similar to grinding the release surface 50a of the Si substrate 50, the holding stage 20 is rotated counterclockwise when viewed from above, and the spindle 68 is rotated counterclockwise when viewed from above. Then, the spindle 68 is lowered so that the grinding stone 76 contacts the release surface 4' of the Si ingot 2. Afterward, the spindle 68 is lowered at a predetermined grinding feed rate. This allows grinding of the release surface 4' of the Si ingot 2, planarizing the crystal surface (100) of the Si ingot 2. It should be noted that other grinding apparatuses having the same grinding mechanism as the grinding apparatus 52 can also be used to perform the planarization process in parallel with the wafer grinding process. Alternatively, after grinding the release surface 4', a suitable grinding apparatus can be used to grind the planarized crystal surface (100) until the desired surface roughness is achieved.

[0072] After the planarization process, multiple Si substrates 50 are manufactured from the Si ingot 2 by repeatedly performing the stripping formation process, indexing feed process, wafer manufacturing process, wafer grinding process, and planarization process described above. In this embodiment, since the first end face 4 of the Si ingot 2 is the surface that makes the crystal surface (100) flat, an example starting from the stripping formation process has been described. However, if the first end face 4 of the Si ingot 2 is not the surface that makes the crystal surface (100) flat, it is also possible to start from the planarization process.

[0073] As described above, in the Si substrate manufacturing method of this embodiment, a release layer 40 is formed by irradiating a pulsed laser beam LB on a Si ingot 2, and a Si substrate 50 is peeled off from the Si ingot 2 starting from the release layer 40. Therefore, the Si substrate 50 can be manufactured efficiently from the Si ingot 2 without cutting.

[0074] Explanation of symbols

[0075] 2: Si ingot

[0076] 4: First end face (the face that makes the crystal plane (100) a flat surface)

[0077] 12: The intersection line of crystal plane {100} and crystal plane {111}

[0078] 38: Peeling band

[0079] 40: Peeling layer

[0080] 50: Si substrate

[0081] LB: Laser beam

[0082] FP: Spotlight

Claims

1. A method for manufacturing a Si substrate, comprising the steps of manufacturing a Si substrate from a Si ingot having a flat crystal plane (100), the method comprising the following steps: In the stripping band formation process, the focal point of a laser beam of wavelength that is transparent to Si is positioned at a depth from the flat surface equivalent to the thickness of the Si substrate to be manufactured, while the focal point is aligned with the Si ingot in a direction parallel to the intersection line of crystal planes {100} and {111}. <110> The upper and lower parts move relative to each other, while laser light is irradiated onto the Si ingot to form a peeling zone; The indexing feed process involves indexing the focusing point relative to the Si ingot in a direction orthogonal to the direction in which the separation band is formed; and In the wafer manufacturing process, the release strip formation process and the indexing feed process are repeatedly performed to form a release layer inside the Si ingot that is parallel to the crystal plane (100) as a whole. The Si substrate is then peeled off from the release layer of the Si ingot. In the stripping band formation process, the focal point of the laser beam is branched into multiple branches in the indexing feed direction, and these multiple branched focal points form the portions where the crystal structure is destroyed. The division size in the indexing feed process is greater than the width of the portion of the crystal structure that is damaged, in a direction orthogonal to the direction in which the peeling band is formed.

2. The Si substrate manufacturing method as described in claim 1, wherein, In this indexing feed process, indexing is performed in a manner that adjacent stripping strips come into contact.

3. The Si substrate manufacturing method as described in claim 1, wherein, Prior to the stripping band formation process, a planarization process is further included to planarize the crystal surface (100) of the Si ingot.

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