peeling device

Abstract

To provide a peeling device which can solve a problem of damage due to a dropout of a wafer from an upper surface of an ingot in the case where the wafer is peeled from the ingot by applying an ultrasonic sound from the upper surface of the ingot and sucked and exported.SOLUTION: A peeling device comprises: holding means 60 for holding an ingot 10; water supply means 88 for forming a layer of water to an upper surface 12 of the ingot 10; ultrasonic sound means 78 for applying an ultrasonic sound to the upper surface 12 of the ingot 10 via the layer of water; peeling confirmation means 87 for confirming peeling of a wafer 19 to be generated; wafer exporting means 90 for dropping a suction pad 95 having a suction surface 95a opposite to the upper surface 12 of the ingot 10, sucking the wafer 19 to be generated, and exporting the wafer from the ingot 10; and control means 100. The control means 100 positions the water supply means 88, the ultrasonic sound means 78, and the peeling confirmation means 87 at a saving position after the peeling confirmation means 87 confirms the peeling of the wafer 19, and operates the wafer exporting means 90 to export the wafer 19 from the ingot 10.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a peeling device that peels a wafer from an ingot in which a peeling layer is formed at a depth corresponding to the wafer to be produced.

Background Art

[0002] Devices such as power devices and LEDs are formed by laminating a functional layer on the surface of a wafer using single crystal SiC as a material and partitioning it by a planned division line.

[0003] The wafers on which devices are formed are generally produced by slicing an ingot with a wire saw, and the front and back surfaces of the sliced wafers are polished to a mirror finish (see, for example, Patent Document 1).

[0004] In addition, when a single crystal SiC ingot is cut with a wire saw and the front and back surfaces are polished to produce a wafer, 70 to 80% of the ingot is discarded, which is uneconomical. Therefore, the applicant has proposed a technique of positioning the focus point of a laser beam having a wavelength that is permeable to single crystal SiC inside the ingot, irradiating it, forming a peeling layer on the planned cutting surface, and peeling the wafer (see Patent Document 2).

[0005] According to the technique of Patent Document 2 described above, the problem that 70 to 80% of the ingot is discarded is solved, and the problem of uneconomicalness is solved. However, it is relatively difficult to peel the wafer from the peeling layer formed by the laser beam, and there is a problem that the production efficiency is poor. Therefore, the applicant has proposed a peeling device that forms a layer of water on the upper surface of the wafer to be produced and applies ultrasonic waves to peel the wafer to be produced from the ingot (see Patent Document 3).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] According to the technology described in Patent Document 3 above, it becomes possible to efficiently detach wafers from ingots, thus resolving the problem of poor productivity. However, when applying ultrasound to the top surface of the ingot to detach the wafer from the ingot and then removing it from the detachment device by suction, it is difficult to determine the timing at which the wafer completely detaches from the ingot. If an attempt is made to remove the wafer by suction after this detachment timing has passed, problems such as the wafer detached from the top surface of the ingot falling off with the flow of water and being damaged occur.

[0008] The present invention has been made in view of the above facts, and its main technical problem is to provide a peeling device that solves problems such as wafers falling off and being damaged when ultrasonic waves are applied from the top surface of an ingot to peel the wafer from the ingot, suck it up, and transport it away. [Means for solving the problem]

[0009] To solve the above-mentioned main technical problems, the present invention provides a peeling apparatus for peeling a wafer from an ingot in which a peeling layer is formed at a depth corresponding to the wafer to be produced, comprising: a holding means for holding the ingot; a water supply means for forming a layer of water on the upper surface of the ingot; an ultrasonic means for applying ultrasonic waves to the upper surface of the ingot through the water layer; a peeling confirmation means for confirming the peeling of the wafer to be produced; a wafer removal means for lowering a suction pad equipped with a suction surface facing the upper surface of the ingot to suck up the wafer to be produced and remove it from the ingot; and a control means. The delamination confirmation means is a means for confirming the start of delamination originating from the delamination layer by detecting a change in height at the start of delamination that is smaller than the change in height at which the wafer completely delaminates and falls off from the ingot. The control means is that the peeling confirmation means is of the wafer Applicable Peeling startAfter confirming this, the water supply means, the ultrasonic means, and the peeling confirmation means are positioned in a retracted position, and the wafer unloading means is activated to unload the wafer from the ingot. [Effects of the Invention]

[0010] The peeling apparatus of the present invention is a peeling apparatus for peeling a wafer from an ingot in which a peeling layer is formed to a depth corresponding to the wafer to be produced, and includes a holding means for holding the ingot, a water supply means for forming a layer of water on the upper surface of the ingot, an ultrasonic means for applying ultrasonic waves to the upper surface of the ingot through the layer of water, a peeling confirmation means for confirming the peeling of the wafer to be produced, a wafer removal means for lowering a suction pad equipped with a suction surface facing the upper surface of the ingot to suck up the wafer to be produced and remove it from the ingot, and a control means. The delamination confirmation means is a means for confirming the start of delamination originating from the delamination layer by detecting a change in height at the start of delamination that is smaller than the change in height at which the wafer completely delaminates and falls off from the ingot. The control means is that the peeling confirmation means is of the wafer Applicable Peeling start After confirming this, the water supply means, ultrasonic means, and peeling confirmation means are positioned in a retracted position and the wafer removal means is activated to remove the wafer from the ingot. Therefore, by knowing the appropriate peeling timing of the wafer to be produced by the peeling confirmation means, the wafer to be produced can be reliably removed from the ingot by the wafer removal means, and the problem of wafers falling off and being damaged is eliminated. [Brief explanation of the drawing]

[0011] [Figure 1] This is the ingot processed in this embodiment. [Figure 2] This is a perspective view showing an ingot shown in Figure 1 that has been subjected to a delamination layer formation process. [Figure 3] (a) A plan view of an ingot in which a peeling layer has been formed by the peeling layer formation process shown in Figure 2, and (b) An enlarged cross-sectional view of the AA section in (a). [Figure 4] This is an overall perspective view of the peeling apparatus of this embodiment. [Figure 5](a) A perspective view showing the state when the wafer to be produced is peeled off by the peeling device shown in Figure 4, and (b) A side view showing the manner in which ultrasound is applied in (a). [Figure 6] This is a perspective view showing a configuration in which the wafer unloading mechanism is positioned close to the ingot. [Figure 7] This is a perspective view showing the state after the wafer has been removed by the wafer removal means. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the peeling apparatus configured according to the present invention will be described in detail with reference to the attached drawings.

[0013] Figures 1(a) and 1(b) show an ingot 10 for producing wafers to be peeled off by a peeling device 50 (see Figure 4) described later, in its state before the peeling layer (described later) is formed. The ingot 10 of this embodiment is formed in a substantially cylindrical shape overall from hexagonal single crystal SiC, and has a circular first end face 12, a circular second end face (not numbered) on the opposite side of the first end face 12 to which the substrate 20 is attached, a circumferential surface 13 located between the first end face 12 and the second end face, and a c-axis ( <0001> The ingot has a direction (P) and a c-plane ({0001} plane) perpendicular to the c-axis. In the illustrated ingot 10, the c-axis is inclined with respect to a perpendicular line 18 passing through the center 16 of the first end face 12 shown in Figure 1(a) (see Figure 1(b)), and an off-angle α (for example, α = 1, 3, 6 degrees) is formed between the c-plane and the first end face 12. The direction in which the off-angle α is formed is indicated by arrow P in Figures 1(a) and (b). In addition, a rectangular first orientation flat 14 and a second orientation flat 15 indicating the crystal orientation are formed on the circumferential surface 13 of the ingot 10. The first orientation flat 14 is parallel to the direction P in which the off-angle α is formed, and the second orientation flat 15 is perpendicular to the direction P in which the off-angle α is formed. The length of the second orientation flat 15 is set to be shorter than the length of the first orientation flat 14, thereby specifying the front and back sides of the ingot 10 and the inclination direction of the off-angle α. The ingot 10 from which the wafer is peeled by the peeling device 50 described later is not limited to the ingot 10 described above, and may be, for example, a single-crystal SiC ingot in which the c-axis is not tilted with respect to the perpendicular of the end face of the ingot and the off-angle between the c-plane and the end face is 0 degrees (i.e., the perpendicular of the end face and the c-axis are 1), or an ingot formed from a material other than single-crystal SiC, such as Si (silicon) or GaN (gallium nitride).

[0014] In order to peel the wafer from the ingot 10 with the peeling device 50 described below, it is necessary to form a peeling layer on the ingot 10. The formation of the peeling layer can be carried out, for example, using the laser processing device 30 shown in FIG. 2 (only a part is shown). The laser processing device 30 includes a chuck table (not shown) for holding the workpiece and laser beam irradiation means 32 including a condenser 34 for irradiating the workpiece held on the chuck table with a pulsed laser beam LB. The chuck table is configured to suck and hold the workpiece on its upper surface, and includes rotation driving means, X-axis moving means, and Y-axis moving means (not shown), and can move the held ingot 10 relative to the condenser 34 and position it at an arbitrary XY coordinate position. The condenser 34 includes a condenser lens (not shown) for condensing the pulsed laser beam LB oscillated by a pulsed laser beam oscillator (not shown) of the laser processing device 30 and irradiating the workpiece.

[0015] Continuing the description with reference to FIG. 2, when forming the peeling layer on the ingot 10, first, the first end face 12 of the ingot 10 is turned upward, the second end face side with the substrate 20 attached is turned downward, and the ingot 10 is sucked and held on the upper surface of the chuck table. Next, the ingot 10 is imaged from above by imaging means (not shown) of the laser processing device 30. Next, based on the image of the ingot 10 imaged by the imaging means, the X-axis moving means, Y-axis moving means, and rotation driving means of the laser processing device 30 are operated to adjust the orientation of the ingot 10 to a predetermined orientation and position the ingot 10 at a predetermined XY position. When adjusting the orientation of the ingot 10 to a predetermined orientation, as shown in FIG. 2, by aligning the second orientation flat 15 in the X-axis direction, the direction orthogonal to the direction P in which the off-angle α is formed is aligned with the X-axis direction, and the direction P in which the off-angle α is formed is aligned with the Y-axis direction.

[0016] Next, the condenser 34 is moved up and down by the condensing point position adjusting means (not shown) of the laser processing apparatus 30, and the condensing point is positioned at a depth corresponding to the thickness of the wafer to be formed from the first end face 12 of the ingot 10. Next, a pulsed laser beam LB having a wavelength that is transmissive to single-crystalline SiC is irradiated from the condenser 34 onto the ingot 10, and the ingot 10 is moved in the X-axis direction that is aligned with the direction perpendicular to the direction P in which the off-angle α is formed to perform a peeling layer forming process for forming the peeling layer 40. In this peeling layer forming process, as understood from FIG. 3(a) and FIG. 3(b) which is an enlarged view of the cross section taken along the line A-A in FIG. 3(a), SiC is separated into Si (silicon) and C (carbon) by the irradiation of the pulsed laser beam LB, and then the pulsed laser beam LB irradiated next is absorbed by the C formed previously, and a modified portion 42 in which SiC is continuously separated into Si and C is continuously formed in the X-axis direction. At the same time, cracks 44 that extend isotropically along the c-plane are generated from the modified portion 42. When the modified portion 42 and the cracks 44 are thus formed, the ingot 10 is indexed and fed in the Y-axis direction by a predetermined index amount L, and the above-described laser processing is repeated. Thereby, a peeling layer 40 having a reduced strength for peeling the wafer from the ingot 10, which is composed of a plurality of modified portions 42 and cracks 44, can be formed at a depth corresponding to the thickness of the wafer to be formed from the first end face 12 of the ingot 10.

[0017] Incidentally, the peeling layer forming process for forming the above-described peeling layer 40 can be performed under, for example, the following processing conditions. Wavelength of pulsed laser beam: 1064 nm Repetition frequency: 60 kHz Average output: 1.5 W Pulse width: 4 ns Spot diameter: 3 μm Numerical aperture (NA) of condenser lens: 0.65 Processing feed rate: 200 mm / s

[0018] FIG. 4 shows a peeling apparatus 50 of the present embodiment for peeling a wafer from the ingot 10 on which the above-described peeling layer 40 is formed.

[0019] The peeling apparatus 50 includes a holding means 60 for holding the ingot 10, a water supply means 88 for forming a layer of water on the upper surface of the ingot 10, an ultrasonic means 78 for applying ultrasonic waves to the upper surface of the ingot through the water layer, a peeling confirmation means 87 for confirming the peeling of the wafer to be produced, a wafer removal means 90 for lowering a suction pad 95 equipped with a suction surface 95a facing the upper surface (first end face 12) of the ingot 10 to suck up the wafer to be produced and remove it from the ingot 10, and a control means 100.

[0020] The holding means 60 includes a rectangular movable plate 61 mounted on the base 51 of the peeling device 50 so as to be movable in the X-axis direction indicated by arrow X in the figure, a cylindrical support column 62 fixed to the upper surface of the movable plate 61, and a holding table 64 disposed at the upper end of the support column 62 to hold the ingot 10 described above and configured to be rotatable by a rotational drive means (not shown). The holding table 64 has a circular suction chuck 64a made of a porous material and extending substantially horizontally on its upper surface. The suction chuck 64a is connected to a suction means (not shown) by a flow path through the support column 62. The holding means 60 includes a moving means 67 for moving the holding table 64 in the X-axis direction. The moving means 67 converts the rotational motion of the motor 65 into linear motion via a ball screw 66 and transmits it to the movable plate 61, causing the movable plate 61 to move back and forth in the X-axis direction along a pair of guide rails 51A, 51A arranged parallel to each other along the X-axis direction on the base 51. Although not shown in the diagram, the holding means 60 is equipped with a position detection means, which accurately detects the position of the holding table 64 in the X direction and its rotational position in the circumferential direction. Based on the signals instructed by the control means 100, the moving means 67 and the rotational drive means are driven, making it possible to accurately position the holding table 64 at any position and rotational angle in the X direction.

[0021] On the base 51 of the peeling device 50, on the rear side in the X-axis direction, a pair of guide rails 51A, 51A are sandwiched between a first positioning means 70 and a second positioning means 80. The first positioning means 70 comprises a cylinder 72, a lifting rod 74 that is raised and lowered by the cylinder 72, and a swivel arm 76 disposed at the upper end of the lifting rod 74 and configured to be rotatable by the action of the cylinder 72. The tip of the swivel arm 76 is equipped with an ultrasonic means 78 that applies ultrasonic vibrations from the lower surface 78a to the ingot 10 positioned at a predetermined peeling position. The second positioning means 80 comprises a cylinder 82, a lifting rod 84 that is raised and lowered by the cylinder 82, and a swivel arm 86 disposed at the upper end of the lifting rod 84 and configured to be rotatable by the action of the cylinder 82. Displaced at the tip of the swivel arm 86 is a peeling confirmation means 87 for confirming the peeling of wafers to be produced from the ingot 10 positioned at a predetermined peeling position, and a water supply means 88 for forming a layer of water on the upper surface of the ingot 10.

[0022] The ultrasonic means 78, the delamination confirmation means 87, and the water supply means 88 are appropriately controlled by the control means 100. The ultrasonic means 78, for example, provides an output of 100W and a vibration frequency of 25kHz. The delamination confirmation means 87 is configured, for example, by a so-called proximity sensor and is a means for detecting changes in the surface height of the first end face 12 of the ingot 10 positioned directly below the delamination confirmation means 87 (the surface height changes as the first end face 12 lifts away from the ingot due to the start of delamination). The proximity sensor constituting the delamination confirmation means 87 is not particularly limited and may be an ultrasonic type sensor that irradiates the ingot 10 with ultrasonic waves, detects the reflected wave, and detects the height position to which the ultrasonic waves were irradiated based on the return time of the reflected wave, or it may be another proximity sensor, such as an electromagnetic wave type or an infrared type sensor. The water supply means 88 is connected to a water supply source (not shown) via a vertical part 91 and a horizontal part 92, and water is supplied from below, for example, 3 liters per minute.

[0023] The wafer unloading means 90 is located at the rear end of the peeling device 50 in the X-axis direction, and is positioned at the opposite end from the moving means 67, which is positioned on one end of the pair of guide rails 51A, 51A. The wafer unloading means 90 comprises a vertical section 91 erected on the base 51, a horizontal section 92 positioned at the upper end of the vertical section 91 and extending horizontally, a cylinder 93 positioned at the end of the horizontal section 92, a lifting rod 94 raised and lowered by the cylinder 93, and a suction pad 95 positioned at the lower end of the lifting rod 94 and having a suction surface 95a on its lower side. The horizontal section 92 is provided with a suction port 96 for generating negative pressure on the suction surface 95a of the suction pad 95, and the suction port 96 is connected to a suction source (not shown).

[0024] The holding table 64 moves forward and backward in the X-axis direction by operating the moving means 67 described above, and can be moved between the loading / unloading position where the holding table 64 is positioned in Figure 4 and the delamination position which is directly below the suction pad 95 of the wafer loading means 90. Also in Figure 4, the ultrasonic means 78, the delamination confirmation means 87, and the water supply means 88 are positioned in a retracted position that does not obstruct the raising and lowering of the suction pad 95 by the action of the first positioning means 70 and the second positioning means 80.

[0025] The peeling apparatus 50 of this embodiment has a configuration that is generally as described above, and the following describes how the peeling apparatus 50 of this embodiment is used to peel off wafers from an ingot and transport them out.

[0026] An ingot 10, on which a peeling layer 40 has been formed to a depth corresponding to the wafer to be produced by the peeling layer formation process described above, is loaded into a peeling apparatus 50 as described with reference to Figure 4. Next, the ingot 10 is placed with the substrate 20 side facing downwards on the suction chuck 64a of the holding table 64 at the loading / unloading position where the holding table 64 is positioned in Figure 4, and is held in place by activating a suction means (not shown).

[0027] At the loading / unloading position, the holding table 64 that holds the ingot 10 is moved to the peeling position, directly below the suction pad 95 of the wafer loading means 90, by operating the moving means 67. At this time, the suction pad 95 is moved by the action of the cylinder 93 to an upper position that does not obstruct the movement of the ultrasonic means 78, peeling confirmation means 87, and water supply means 88.

[0028] Next, the cylinder 82 of the second positioning means 80 raises the peeling confirmation means 87 and the water supply means 88 to a position where they are at a sufficient distance from the first end face 12 of the ingot 10 and do not come into contact with it, even when the swivel arm 86 is swiveled. At the same time, the swivel arm 86 is rotated to move the peeling confirmation means 87 and the water supply means 88 onto the first end face 12 of the ingot 10, as shown in Figure 5(a). Next, the height position of the first end face 12 of the ingot 10 is detected by the action of a proximity sensor (not shown) attached to the peeling confirmation means 87, and the lower surfaces of the peeling confirmation means 87 and the water supply means 88, which are set to the same height, are positioned at a predetermined height (for example, 2 mm) from the first end face 12. Next, the cylinder 72 rotates the swivel arm 76 to position the ultrasonic means 78 onto the first end face 12 of the ingot 10, as shown in Figure 5(a). When rotating the ultrasonic means 78, the height of the first end face 12 of the ingot 10 is detected in advance by the delamination confirmation means 87 and stored in the control means 100. Based on this stored information, the cylinder 72 is operated to adjust the height position of the ultrasonic means 78, and the height from the first end face 12 of the ingot 10 to the lower surface 78a of the ultrasonic means 78 is set to the same height as or lower than that of the delamination confirmation means 87 and the water supply means 88 (for example, 1 mm).

[0029] As described above, once the delamination confirmation means 87, water supply means 88, and ultrasonic means 78 are positioned on the first end face 12 of the ingot 10 (see Figure 5(b)), the water supply means 88 supplies 3 liters of water 89 per minute onto the first end face 12 of the ingot 10. The amount of water 89 supplied at this time is the amount that forms a layer of water 89 between the lower surface 78a of the ultrasonic means 78 and the first end face 12 of the ingot 10, and between the lower surface of the delamination confirmation means 87 and the first end face 12 of the ingot 10. The amount of water 89 supplied is appropriately changed according to the dimensions between the lower surface 78a of the ultrasonic means 78 and the first end face 12 of the ingot 10, and between the lower surface of the delamination confirmation means 87 and the first end face 12 of the ingot 10.

[0030] As described above, with a sufficient amount of water 89 supplied from the water supply means 88 and a layer of water 89 formed, the holding table 64 is rotated in the direction indicated by arrow R1 in Figure 5, and ultrasonic waves are emitted from the lower surface 78a of the ultrasonic means 78 to apply ultrasonic waves to the entire area of ​​the first end face 12 of the ingot 10. While the ultrasonic waves are being applied, the peeling confirmation means 87 is activated to detect changes in the height position of the first end face 12 of the ingot 10. By applying the above-described ultrasonic waves to the first end face 12 of the ingot 10, the ultrasonic waves are transmitted to the first end face 12 of the ingot 10 via the water 89, causing the cracks 44 in the peeling layer 40 to extend, and as the peeling of the ingot 10 progresses starting from the peeling layer 40, the height position of the first end face 12 of the ingot 10 changes upward. In this embodiment, before using the wafer unloading means 90 to unload the wafer from the first end face 12 side of the ingot 10, a delamination state is detected in which the wafer to be produced does not detach from the ingot 10 and is in a state where the wafer can be unloaded by the wafer unloading means 90, in order to prevent the wafer to be unloaded from falling off the ingot 10 and being damaged. More specifically, the delamination confirmation means 87 detects a change in height at the start of delamination (for example, set to 5 to 10 μm) that is smaller than the change in height at which the wafer completely delaminates and falls off the ingot 10. The time from the start of application of ultrasound to the detection of the start of delamination is approximately 20 to 30 seconds.

[0031] As described above, once the peeling confirmation means 87 confirms the start of peeling starting from the peeling layer 40, the operation of the water supply means 88, the ultrasonic means 78, and the peeling confirmation means 87 is stopped and they are positioned in the retracted position described above. This retracted position is, for example, the position in Figure 4 where the water supply means 88, the ultrasonic means 78, and the peeling confirmation means 87 are positioned, and is a position that does not hinder the raising and lowering of the suction pad 95 of the wafer removal means 90. Next, as shown in Figure 6, the suction pad 95 of the wafer removal means 90 is lowered so that the suction surface 95a of the suction pad 95 comes into contact with the first end face 12 of the ingot 10, and a suction means (not shown) is activated to draw air from the suction port 96 described above to generate negative pressure on the suction surface 95a, and the first end face 12 of the ingot 10 is drawn in by the suction surface 95a. Next, by raising the suction pad 95 of the wafer removal means 90, the wafer 19, whose thickness is defined by the delamination layer 40, is peeled off from the delamination layer 40 of the ingot 10 and removed, as shown in Figure 7 (in Figure 7, the suction pad 95 of the wafer removal means 90 is omitted for illustrative purposes). The new first end face 12' of the ingot 10 from which the wafer 19 has been removed has a rough delamination surface due to the delamination layer formation process described above. Before generating a new wafer 19, it is polished by a polishing means to a mirror finish that allows for the delamination layer formation process described above to be carried out.

[0032] The wafer 19, removed from the ingot 10, is transported to the next process by other transport mechanisms (not shown in the diagram) or placed in a container (not shown in the diagram).

[0033] According to the above-described embodiment, by knowing the appropriate timing for peeling the wafer to be produced using the peeling confirmation means, the wafer to be produced can be reliably delivered from the ingot by the wafer delivery means 90, thus eliminating the problem of wafers falling off and being damaged. [Explanation of Symbols]

[0034] 10: Ingot 12: First end face 13: Peripheral surface 14: First Orientation Flat 15: Second Orientation Flat 16: Center 18: Perpendicular line 19: Waha 20: Substrate 30: Laser processing equipment 32: Laser beam irradiation means 34: Light concentrator 40: Exfoliation layer 42: Modification section 44: Crack 50: Peeling device 51: Base 51A: Guide rail 60: Holding means 61: Movable plate 62: Post 64: Holding Table 64a: Suction chuck 65: Motor 66: Ball screw 67: Means of transportation 70: First positioning means 72: Cylinders 74: Lifting rod 76: Swivel Arm 78: Ultrasonic means 78a: Bottom surface 80: Second positioning means 82: Cylinder 84: Lifting rod 86: Swivel Arm 87: Means for confirming peeling 88:Water supply means 89:Water 90: Wafer removal means 91:Vertical part 92:Horizontal part 93: 1 / 2 94: Lifting rod 95: Suction pads 95a: Suction surface 96: Suction port 100: Control means

Claims

[Claim 1] A peeling apparatus for peeling a wafer from an ingot in which a peeling layer has been formed at a depth corresponding to the wafer to be produced, The system includes a holding means for holding an ingot, a water supply means for forming a layer of water on the upper surface of the ingot, an ultrasonic means for applying ultrasonic waves to the upper surface of the ingot through the water layer, a peeling confirmation means for confirming the peeling of the wafer to be produced, a wafer removal means for lowering a suction pad with a suction surface facing the upper surface of the ingot to suck up the wafer to be produced and remove it from the ingot, and a control means. The delamination confirmation means is a means for confirming the start of delamination originating from the delamination layer by detecting a change in height at the start of delamination that is smaller than the change in height at which the wafer completely delaminates and falls off from the ingot. The control means, after the peeling confirmation means confirms the start of peeling of the wafer, positions the water supply means, the ultrasonic means, and the peeling confirmation means in a retracted position and operates the wafer removal means to remove the wafer from the ingot.

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