Wafer Generation Equipment

Abstract

To provide a wafer manufacturing apparatus that is capable of preventing wafers from being reduced in quality.SOLUTION: A wafer manufacturing apparatus 2 includes at least: an ingot grinding unit 4 for grinding an upper surface of an ingot 230 to planarize the upper surface; a laser applying unit 6 for forming peel-off layers at a depth that corresponds to a thickness of a wafer to be produced from the upper surface of the ingot 230; a wafer peeling unit 8 for holding the upper surface of the ingot 230 and peeling off a wafer from the peel-off layers; a tray 9 including an ingot support portion and a wafer support portion; and a belt conveyor unit 10 for delivering the ingot 230 supported on the tray 9 between the ingot grinding unit 4, the laser applying unit 6, and the wafer peeling unit 8. A quality inspecting unit 13 is disposed adjacent to the belt conveyor unit 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wafer producing apparatus for producing wafers from an ingot. [Background technology]

[0002] Devices such as ICs, LSIs, and LEDs are formed by laminating functional layers on the surface of wafers made of materials such as Si (silicon) and Al2O3 (sapphire), and then dividing the wafer into sections along planned division lines. Power devices, LEDs, and the like are formed by laminating functional layers on the surface of wafers made of single crystal SiC (silicon carbide), and then dividing the wafer into sections along planned division lines. Wafers with devices formed on them are processed along the planned division lines by cutting equipment and laser processing equipment, and then divided into individual devices, and each divided device is used in electrical equipment such as mobile phones and personal computers.

[0003] Wafers on which devices are formed are generally produced by thinly slicing a cylindrical ingot with a wire saw. The front and back surfaces of the sliced ​​wafers are polished to a mirror finish (see, for example, Patent Document 1). However, when an ingot is sliced ​​with a wire saw and the front and back surfaces of the sliced ​​wafers are polished, most of the ingot (70 to 80%) is discarded, which is uneconomical. In particular, single crystal SiC ingots have high hardness, making cutting with a wire saw difficult and time-consuming, resulting in poor productivity, and the high unit price of the ingot makes it difficult to efficiently produce wafers.

[0004] Therefore, a technology has been proposed in which the focal point of a laser beam having a wavelength that is transparent to single crystal SiC is positioned inside a single crystal SiC ingot, the laser beam is irradiated onto the single crystal SiC ingot to form a peeling layer on the planned cutting surface, and a wafer is peeled off from the single crystal SiC ingot along the planned cutting surface on which the peeling layer has been formed (see, for example, Patent Document 2).

[0005] Furthermore, Patent Document 2 discloses a technology for efficiently carrying out a series of operations in which several (e.g., four) transport trays containing ingots are constantly placed on a conveyor belt, the ingots are transported to each processing unit to produce wafers from the ingots, the produced wafers are stored on the same transport tray as the ingots, and in the wafer unloading area, the wafers are stored in a cassette linked to the ingot. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2000-94221 A [Patent Document 2] JP 2020-72098 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, even if the top surface of the ingot is flattened by a grinding means, there are cases in which the top surface of the ingot is not sufficiently flattened. In such cases, the focal point of the laser beam that next forms the peeling layer is not focused at an appropriate position inside the ingot, resulting in a problem of reduced quality of the wafer to be peeled off from the ingot.

[0008] In view of the above, an object of the present invention is to provide a wafer preparation apparatus capable of preventing deterioration in the quality of wafers. [Means for solving the problem]

[0009] According to the present invention, there is provided the following wafer production apparatus that solves the above problems: That is, the wafer production apparatus produces wafers from an ingot, and includes an ingot grinding unit including at least a first holding table for holding the ingot and grinding means for grinding and flattening the top surface of the ingot held on the first holding table, and a laser including at least a second holding table for holding the ingot and laser irradiation means for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth from the top surface of the ingot held on the second holding table that corresponds to the thickness of the wafer to be produced, and irradiating the ingot with the laser beam to form a peeled layer. a wafer separation unit including at least a third holding table for holding an ingot and a wafer separation means for holding an upper surface of the ingot held on the third holding table and separating the wafer from the separation layer; a tray including an ingot support portion for supporting the ingot and a wafer support portion for supporting the separated wafer; and a belt conveyer unit for transporting the ingot supported on the tray between the ingot grinding unit, the laser irradiation unit, and the wafer separation unit, and a quality inspection unit is disposed adjacent to the belt conveyer unit. The quality inspection unit includes an ingot quality inspection unit that inspects whether or not there is a defect on the upper surface of the ingot ground by the ingot grinding unit that prevents the laser beam of the laser irradiation unit from being incident thereon. A wafer preparation apparatus is provided.

[0010] Preferably, the quality inspection unit comprises: A wafer quality inspection unit that inspects the quality of a wafer peeled off from an ingot, the wafer quality inspection unit comprising: The apparatus includes an illuminator, an imaging means for receiving light reflected from the upper surface of the wafer by the light illuminator, and a defect detection means for processing the image captured by the imaging means and detecting defects. ingot The quality inspection unit preferably includes an illuminator, an imaging means for receiving light reflected from the top surface of the ingot by the light of the illuminator, and a defect detection means for processing the image captured by the imaging means and detecting defects. The present invention also provides the following wafer production apparatus that solves the above problems: That is, the wafer production apparatus produces wafers from an ingot, and includes an ingot grinding unit including at least a first holding table for holding an ingot and grinding means for grinding and flattening an upper surface of the ingot held on the first holding table, a laser irradiation unit including at least a second holding table for holding an ingot and laser irradiation means for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of a wafer to be produced from the upper surface of the ingot held on the second holding table and irradiating the ingot with a laser beam to form a peeling layer, and a wafer peeling unit including at least a third holding table for holding an ingot and wafer peeling means for holding the upper surface of the ingot held on the third holding table and peeling a wafer from the peeling layer. The present invention provides a wafer generation apparatus comprising at least a tray having an ingot support portion for supporting an ingot and a wafer support portion for supporting a peeled wafer, and a belt conveyor unit for transporting the ingot supported on the tray between the ingot grinding unit, the laser irradiation unit, and the wafer peeling unit, wherein a quality inspection unit is disposed adjacent to the belt conveyor unit, and the quality inspection unit includes a wafer quality inspection unit for inspecting the quality of the wafer peeled from the ingot, the wafer quality inspection unit including an illuminator, an imaging means for receiving light reflected from the top surface of the wafer by the illuminator, a defect detection means for processing the image captured by the imaging means and detecting defects, and a wafer conveyor belt for moving the wafer parallel to the top surface of the wafer when the wafer is imaged by the imaging means. Effect of the Invention

[0011] The wafer generating apparatus of the present invention includes an ingot grinding unit including at least a first holding table for holding an ingot and a grinding means for grinding and flattening the top surface of the ingot held on the first holding table, a laser irradiation unit including at least a second holding table for holding an ingot and a laser irradiation means for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of a wafer to be generated from the top surface of the ingot held on the second holding table, and irradiating the ingot with the laser beam to form a peeling layer, and The apparatus includes at least a wafer separation unit including at least a third holding table for holding an ingot and a wafer separation means for holding an upper surface of the ingot held on the third holding table and separating the wafer from the separation layer, a tray including an ingot support portion for supporting the ingot and a wafer support portion for supporting the separated wafer, and a belt conveyer unit for transporting the ingot supported on the tray between the ingot grinding unit, the laser irradiation unit, and the wafer separation unit, and a quality inspection unit is disposed adjacent to the belt conveyer unit. The quality inspection unit includes an ingot quality inspection unit that inspects whether or not there is a defect on the upper surface of the ingot ground by the ingot grinding unit that prevents the laser beam of the laser irradiation unit from being incident thereon. Therefore, deterioration in the quality of the wafer can be prevented. The wafer generating apparatus of the present invention includes an ingot grinding unit at least comprising a first holding table for holding an ingot and grinding means for grinding and flattening the top surface of the ingot held on the first holding table, a laser irradiation unit at least comprising a second holding table for holding an ingot and laser irradiation means for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth from the top surface of the ingot held on the second holding table corresponding to the thickness of the wafer to be generated, and irradiating the ingot with the laser beam to form a peeling layer, a wafer separation unit at least comprising a third holding table for holding an ingot and wafer separation means for holding the top surface of the ingot held on the third holding table and peeling a wafer from the peeling layer, and an ingot supporting device for supporting the ingot. The wafer peeling unit includes at least a tray having an ingot support portion and a wafer support portion for supporting a peeled wafer, and a belt conveyor unit for transporting the ingot supported on the tray between the ingot grinding unit, the laser irradiation unit, and the wafer peeling unit, and a quality inspection unit is disposed adjacent to the belt conveyor unit, the quality inspection unit including a wafer quality inspection unit for inspecting the quality of the wafer peeled from the ingot, the wafer quality inspection unit including an illuminator, an imaging means for receiving light reflected from the top surface of the wafer by the illuminator, a defect detection means for processing the image captured by the imaging means and detecting defects, and a wafer conveyor belt for moving the wafer parallel to the top surface of the wafer when the imaging means captures an image of the wafer, thereby preventing deterioration in wafer quality. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view of a wafer preparation apparatus constructed in accordance with the present invention; [Diagram 2] FIG. 2 is a perspective view of the ingot grinding unit shown in FIG. [Diagram 3] FIG. 3 is a partially enlarged perspective view of the ingot grinding unit shown in FIG. 2 . [Figure 4] FIG. 2 is a perspective view of the laser irradiation unit shown in FIG. 1 . [Diagram 5] FIG. 5 is a block diagram of the laser irradiation means shown in FIG. 4. [Figure 6] FIG. 2 is a perspective view of the wafer separation unit shown in FIG. [Figure 7] FIG. 7 is a partial cross-sectional view of the wafer separation unit shown in FIG. 6. [Figure 8]FIG. 2 is a perspective view of the tray shown in FIG. [Figure 9] FIG. 2 is a partial perspective view of the wafer generating apparatus shown in FIG. [Figure 10] (a) is an oblique view of the trace stopper when the lifting plate is in the passing position, (b) is an oblique view of the trace stopper when the lifting plate is in the stopping position, and (c) is an oblique view of the trace stopper when the lifting plate is in the separated position. [Figure 11] (a) Cross-sectional view of the trace stopper etc. corresponding to the state shown in Figure 10(a), (b) cross-sectional view of the trace stopper etc. corresponding to the state shown in Figure 10(b), (c) cross-sectional view of the trace stopper etc. corresponding to the state shown in Figure 10(c). [Figure 12] FIG. 4A is a perspective view of the transport means with the lift plate in a raised position, and FIG. 4B is a perspective view of the transport means with the lift plate in a lowered position. [Figure 13] FIG. 2 is a perspective view of the ingot stocker shown in FIG. [Figure 14] FIG. 2 is a perspective view of the ingot delivery unit shown in FIG. [Figure 15] 15 is a perspective view of a state in which the ingot stocker shown in FIG. 13 and the ingot delivery unit shown in FIG. 14 are combined. [Figure 16] FIG. 13 is a perspective view showing a modified example of the clutch portion. [Figure 17] 2A is an oblique view showing the state in which the quality of an ingot is inspected by the quality inspection unit shown in FIG. 1; FIG. 2B is a side view showing the state in which the quality of an ingot is inspected by the quality inspection unit shown in FIG. 1; and FIG. 2C is a schematic diagram of an image of the top surface of the ingot captured by the imaging means shown in FIG. [Figure 18] 2A is a perspective view showing a state in which the quality of a wafer is inspected in the quality inspection unit shown in FIG. 1; FIG. 2B is a side view showing a state in which the quality of a wafer is inspected in the quality inspection unit shown in FIG. 1; and FIG. 2C is a schematic diagram of an image of the top surface of the wafer captured by the imaging means shown in FIG. 2A. [Figure 19] (a) Front view of the ingot, (b) top view of the ingot, (c) perspective view of the ingot. [Figure 20]FIG. 13 is a perspective view showing a state in which the ingot is transferred to a second holding table of the laser irradiation unit. [Figure 21] FIG. 2A is a perspective view showing a state in which a release layer forming step is being performed, and FIG. 2B is a front view showing a state in which a release layer forming step is being performed. [Figure 22] (a) Plan view of an ingot on which a peeling layer has been formed, and (b) Cross-sectional view along line BB in (a). [Figure 23] 1A is a perspective view showing a state where the liquid tank body is positioned above a third holding table of the wafer separation unit, and FIG. 1B is a perspective view showing a state where the lower end of the liquid tank body is in contact with the upper surface of the holding table. [Figure 24] FIG. 13 is a perspective view showing a state in which a wafer is peeled off from an ingot by the wafer peeling unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a wafer generating apparatus configured according to the present invention will be described with reference to the drawings.

[0014] 1 includes at least an ingot grinding unit 4, a laser irradiation unit 6, a wafer separation unit 8, a tray 9 having an ingot support portion for supporting an ingot and a wafer support portion for supporting a separated wafer, and a belt conveyor unit 10 for transporting the ingot supported on the tray 9 between the ingot grinding unit 4, the laser irradiation unit 6, and the wafer separation unit 8, and a quality inspection unit 13 is disposed adjacent to the belt conveyor unit 10. The wafer generation apparatus 2 of the illustrated embodiment further includes an ingot stocker 11 for storing the ingot supported on the tray 9, and an ingot delivery unit 12 for delivering the ingot supported on the tray 9 stored in the ingot stocker 11 to the belt conveyor unit 10.

[0015] The ingot grinding unit 4 will be described with reference to FIG. 2. The ingot grinding unit 4 is at least composed of a circular first holding table 14 for holding an ingot, and a grinding means 16 for grinding and flattening the upper surface of the ingot held on the first holding table 14. The ingot grinding unit 4 in the illustrated embodiment includes a rectangular parallelepiped base 18 and a circular turntable 20 rotatably mounted on the upper surface of the base 18. The turntable 20 is rotated by a turntable motor (not shown) built into the base 18, with an axis extending in the Z-axis direction through the radial center of the turntable 20 as the center of rotation. The first holding tables 14 in the illustrated embodiment are mounted in pair on the upper surface of the turntable 20 for rotation, and are arranged point-symmetrically with respect to the radial center (center of rotation) of the turntable 20. By rotating the turntable 20, the first holding table 14 is alternately positioned between a grinding position (a rear position in FIG. 2) where grinding processing is performed by the grinding means 16 and an ingot attachment / detachment position (a front position in FIG. 2) for attaching and detaching the ingot.

[0016] The first holding table 14 is rotated by a first holding table motor (not shown) attached to the underside of the turntable 20 about an axis extending in the Z-axis direction through the radial center of the first holding table 14. A porous suction chuck 22 connected to a suction means (not shown) is disposed on the upper surface of the first holding table 14, and the first holding table 14 sucks and holds the ingot placed on the upper surface of the suction chuck 22 by generating a suction force on the upper surface of the suction chuck 22 by the suction means. The Z-axis direction is the up-down direction indicated by the arrow Z in FIG. 2. The X-axis direction indicated by the arrow X in FIG. 2 is a direction perpendicular to the Z-axis direction, and the Y-axis direction indicated by the arrow Y in FIG. 2 is a direction perpendicular to the X-axis direction and the Z-axis direction. The plane defined by the X-axis direction and the Y-axis direction is substantially horizontal.

[0017] In the illustrated embodiment, as shown in FIG. 2, the grinding means 16 of the ingot grinding unit 4 includes a gate-shaped support frame 24 mounted on the upper surface of the base 18. The support frame 24 has a pair of support columns 26 extending upward from the upper surface of the base 18 at a distance in the Y-axis direction, and a beam 28 that is bridged between the upper ends of the support columns 26 and extends in the Y-axis direction. A spindle housing 30 is supported on the pair of support columns 26 so as to be movable (liftable) in the Z-axis direction via a pair of connecting pieces 32. A pair of lifting motors 34 for moving (lifting) the spindle housing 30 in the Z-axis direction are mounted on the upper surface of the beam 28. The lifting motor 34 is connected to one end of a ball screw (not shown) extending in the Z-axis direction inside the support columns 26, and a nut portion (not shown) of the ball screw is fixed to the connecting piece 32. The rotational motion of the lifting motor 34 is converted into linear motion by the ball screw and transmitted to the connecting piece 32, thereby lifting the spindle housing 30.

[0018] A spindle 36 (see FIG. 3) is supported in the spindle housing 30 so as to be rotatable about an axis extending in the Z-axis direction, and the spindle 36 is rotated about an axis extending in the Z-axis direction by a spindle motor (not shown) built into the spindle housing 30. A disk-shaped wheel mount 38 is fixed to the lower end of the spindle 36, and an annular grinding wheel 42 is fixed to the lower surface of the wheel mount 38 by bolts 40. A plurality of grinding stones 44 are fixed to the outer periphery of the lower surface of the grinding wheel 42, and are arranged in a ring shape at intervals in the circumferential direction. As shown in FIG. 3, the center of rotation of the grinding wheel 42 is displaced with respect to the center of rotation of the first holding table 14 so that the grinding stone 44 passes through the center of rotation of the first holding table 14 when the first holding table 14 is positioned at the grinding position. Therefore, in the grinding means 16, the first holding table 14 and the grinding wheel 42 are rotated relative to each other while the upper surface of the ingot held on the first holding table 14 is brought into contact with the grinding wheel 44, so that the entire upper surface of the ingot can be ground and flattened by the grinding wheel 44. Although the wafer generating apparatus 2 in the illustrated embodiment is provided with a single ingot grinding unit 4, an ingot grinding unit having a grinding wheel for rough grinding and an ingot grinding unit having a grinding wheel for finish grinding may be arranged side by side.

[0019] The laser irradiation unit 6 will be described with reference to Figures 1 and 4. As shown in Figure 1, the laser irradiation unit 6 disposed adjacent to the ingot grinding unit 4 is composed of at least a circular second holding table 60 for holding an ingot, and a laser irradiation means 62 for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of a wafer to be produced from the upper surface of the ingot held on the second holding table 60, and irradiating the ingot with the laser beam to form a peeled layer.

[0020] In the illustrated embodiment, as shown in FIG. 4, the laser irradiation unit 6 includes a rectangular parallelepiped base 64, and a mounting recess 64a extending in the X-axis direction is formed on the upper surface of the base 64, which is recessed downward. The second holding table 60 in the illustrated embodiment is mounted on the mounting recess 64a of the base 64 so as to be movable in the X-axis direction and rotatable around an axis extending in the Z-axis direction. The base 64 is also equipped with an X-axis feed means (not shown) for moving the second holding table 60 in the X-axis direction along the mounting recess 64a, and a second holding table motor (not shown) for rotating the second holding table 60 around an axis extending in the Z-axis direction through the radial center of the second holding table 60. The X-axis feed means may be configured to include, for example, a ball screw connected to the second holding table 60 and extending in the X-axis direction, and a motor for rotating the ball screw. The second holding table motor is moved in the X-axis direction together with the second holding table 60 by the X-axis feed means, and therefore even when the second holding table 60 is moved in the X-axis direction by the X-axis feed means, the second holding table motor rotates the second holding table 60. In addition, a porous suction chuck 66 connected to suction means (not shown) is disposed on the upper surface of the second holding table 60, and the second holding table 60 is adapted to suction-hold the ingot placed on the upper surface of the suction chuck 66 by generating a suction force on the upper surface of the suction chuck 66 by the suction means.

[0021] 4, the laser irradiation means 62 of the laser irradiation unit 6 includes a gate-shaped support frame 68 mounted on the upper surface of the base 64, a casing 70 supported inside the support frame 68, a Y-axis movable member (not shown) attached to the lower end side of the casing 70 so as to be movable in the Y-axis direction, and a Y-axis feed means (not shown) for moving the Y-axis movable member in the Y-axis direction. The Y-axis feed means may be configured to have, for example, a ball screw connected to the Y-axis movable member and extending in the Y-axis direction, and a motor for rotating the ball screw.

[0022] Explaining with reference to FIG. 5 together with FIG. 4, the laser irradiation means 62 further includes a laser oscillator 72 (see FIG. 5) built into the casing 70, a condenser 74 (see FIG. 4 and FIG. 5) attached to the lower end side of the Y-axis movable member so as to be freely raised and lowered, an alignment means 76 (see FIG. 4) attached to the lower end side of the Y-axis movable member at a distance from the condenser 74 in the Y-axis direction, and a focus point position adjustment means (not shown) for adjusting the Z-axis position of the focus point of the pulsed laser beam LB focused by the condenser 74 by raising and lowering the condenser 74. The laser oscillator 72 oscillates a pulsed laser beam LB having a wavelength that is transparent to the ingot. The condenser 74 has a condensing lens (not shown) for focusing the pulsed laser beam LB oscillated by the laser oscillator 72. The alignment means 76 is adapted to image the ingot held on the second holding table 60 and detect the area to be laser processed. The light-focus point position adjustment means may have, for example, a ball screw connected to the condenser 74 and extending in the Z-axis direction, and a motor for rotating the ball screw.

[0023] As shown in FIG. 5, the casing 70 contains a first mirror 78 that is arranged at a distance from the laser oscillator 72 in the X-axis direction and reflects the pulsed laser beam LB oscillated by the laser oscillator 72 with its optical axis in the X-axis direction, thereby converting the optical axis to the Y-axis direction, and a second mirror (not shown) that is arranged at a distance from the first mirror 78 in the Y-axis direction above the condenser 74 and converts the optical axis of the pulsed laser beam LB reflected by the first mirror 78 from the Y-axis direction to the Z-axis direction, and guides the pulsed laser beam LB to the condenser 74.

[0024] The second mirror is attached to the Y-axis movable member, and when the Y-axis movable member is moved by the Y-axis feed means, it moves in the Y-axis direction together with the condenser 74 and the alignment means 76. Then, the optical axis of a pulsed laser beam LB oscillated from the laser oscillator 72 with its optical axis set in the X-axis direction is converted from the X-axis direction to the Y-axis direction by the first mirror 78 and guided to the second mirror, and then the optical axis is converted from the Y-axis direction to the Z-axis direction by the second mirror and guided to the condenser 74, after which the beam is collected by the collecting lens of the condenser 74 and irradiated onto the ingot held on the second holding table 60. In addition, even when the condenser 74 is moved in the Y-axis direction by moving the Y-axis movable member with the Y-axis feed means, or when the condenser 74 is raised and lowered with the focal point position adjustment means, the pulsed laser beam LB oscillated from the laser oscillator 72 parallel to the X-axis direction has its optical axis converted from the X-axis direction to the Y-axis direction by the first mirror 78 and is guided to the second mirror, and the optical axis of the pulsed laser beam LB guided to the second mirror is converted from the Y-axis direction to the Z-axis direction by the second mirror, and is guided to the condenser 74.

[0025] In the laser irradiation means 62, the ingot held on the second holding table 60 is imaged by the alignment means 76 to detect the region to be laser processed, the condenser 74 is raised and lowered by the condenser position adjustment means to position the condenser of the pulsed laser beam LB having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of the wafer to be produced from the upper surface of the ingot held on the second holding table 60, and the ingot held on the second holding table 60 is irradiated with the pulsed laser beam LB while appropriately moving the condenser 74 in the Y-axis direction by the Y-axis feed means, thereby forming a peeling layer with reduced strength inside the ingot. When the ingot held on the second holding table 60 is irradiated with the pulsed laser beam LB, the second holding table 60 may be moved in the X-axis direction by the X-axis feed means.

[0026] The wafer separation unit 8 will be described with reference to Figures 1 and 6. As shown in Figure 1, the wafer separation unit 8 arranged adjacent to the laser irradiation unit 6 is composed of at least a circular third holding table 80 that holds an ingot, and a wafer separation means 82 that holds the upper surface of the ingot held on the third holding table 80 and separates the wafer from the separation layer.

[0027] In the illustrated embodiment, as shown in FIG. 6, the wafer separation unit 8 includes a rectangular parallelepiped base 84, and a mounting recess 84a extending in the X-axis direction is formed on the upper surface of the base 84, which is recessed downward. The third holding table 80 in the illustrated embodiment is mounted on the mounting recess 84a of the base 84 so as to be movable in the X-axis direction. The base 84 is equipped with an X-axis feed means (not shown) for moving the third holding table 80 in the X-axis direction along the mounting recess 84a. The X-axis feed means may have, for example, a ball screw connected to the third holding table 80 and extending in the X-axis direction, and a motor for rotating the ball screw. A porous suction chuck 86 connected to a suction means (not shown) is disposed on the upper surface of the third holding table 80, and the third holding table 80 is configured to suction-hold the ingot placed on the upper surface of the suction chuck 86 by generating a suction force on the upper surface of the suction chuck 86 by the suction means.

[0028] 6, the wafer separation means 82 of the wafer separation unit 8 includes a gate-shaped support frame 88 mounted on the upper surface of a base 84, a casing 90 supported inside the support frame 88, an arm 92 extending in the X-axis direction from a base end supported on the casing 90 so as to be freely raised and lowered, and an arm moving means (not shown) for raising and lowering the arm 92. The arm moving means may have, for example, a configuration including a ball screw connected to the base end of the arm 92 and extending in the Z-axis direction, and a motor for rotating the ball screw.

[0029] The wafer peeling means 82 will be described with reference to FIG. 6 and FIG. 7. As shown in FIG. 6 and FIG. 7, a liquid tank body 94 is fixed to the tip of the arm 92, which cooperates with the third holding table 80 to accommodate liquid when peeling a wafer from an ingot. The liquid tank body 94 has a circular top wall 96 and a cylindrical skirt wall 98 hanging down from the periphery of the top wall 96, and is open at the bottom end. The outer diameter of the skirt wall 98 is formed to be equal to or smaller than the diameter of the third holding table 80, and when the arm 92 is lowered, the bottom end of the skirt wall 98 comes into contact with the top surface of the third holding table 80. A cylindrical liquid supply unit 100 that communicates with the outside and inside of the liquid tank body 94 is attached to the top wall 96, and the liquid supply unit 100 is connected to a liquid supply means (not shown). As shown in FIG. 7, an annular packing 102 is attached to the bottom end of the skirt wall 98. Then, when the arm 92 is lowered by the arm moving means to bring the lower end of the skirt wall 98 into close contact with the upper surface of the third holding table 80, a liquid containing space 104 is defined by the upper surface of the third holding table 80 and the inner surface of the liquid tank body 94. Liquid 106 supplied to the liquid containing space 104 from the liquid supply means through the liquid supply part 100 is prevented from leaking from the liquid containing space 104 by the packing 102.

[0030] As shown in Fig. 7, an air cylinder 108 is attached to the top wall 96 of the liquid tank body 94, and a cylinder tube 108a of the air cylinder 108 extends upward from the upper surface of the top wall 96. A lower end of a piston rod 108b of the air cylinder 108 passes through a through-hole 96a in the top wall 96 and protrudes below the top wall 96. An ultrasonic vibration generating member 110, which may be made of piezoelectric ceramics or the like, is fixed to the lower end of the piston rod 108b, and an adsorbing piece 112 is fixed to the lower surface of the ultrasonic vibration generating member 110. The adsorbing piece 112, which has a plurality of suction holes (not shown) formed on its lower surface, is connected to a suction means (not shown), and the suction means generates a suction force on the lower surface of the adsorbing piece 112, so that the adsorbing piece 112 sucks and holds the ingot.

[0031] In the wafer peeling means 82, the arm 92 is lowered by the arm moving means to bring the lower end of the skirt wall 98 into close contact with the upper surface of the third holding table 80 holding the ingot on which the peeled layer has been formed, and the piston rod 108b of the air cylinder 108 is lowered to attach the suction piece 112 to the upper surface of the ingot, and then the liquid 106 is contained in the liquid containing space 104, and the ultrasonic vibration generating member 110 is operated to apply ultrasonic vibration to the ingot, thereby further reducing the strength of the peeled layer. In addition, in the wafer peeling means 82, with the upper surface of the ingot being suctioned by the suction piece 112, the suction piece 112 is raised by the air cylinder 108, so that the wafer can be peeled off from the ingot starting from the peeled layer whose strength has been further reduced.

[0032] The tray 9 will be described with reference to Fig. 8. The tray 9 in the illustrated embodiment is composed of a housing including a rectangular upper wall 113, a rectangular lower wall 114 arranged below the upper wall 113, a pair of rectangular side walls 115 connecting the upper wall 113 and the lower wall 114, and a cavity 116 penetrating between the pair of side walls 115. The tray 9 is provided with an ingot support portion 117 on the upper surface of the upper wall 113 for supporting an ingot, and a wafer support portion 118 on the upper surface of the lower wall 114 for supporting a peeled wafer.

[0033] The ingot support portion 117 in the illustrated embodiment has recesses 119 corresponding to ingots of two or more sizes. The recesses 119 have an annular large diameter recess 119a recessed downward from the upper surface of the upper wall 113, and a circular small diameter recess 119b having a smaller diameter than the large diameter recess 119a and recessed further downward than the large diameter recess 119a. The large diameter recess 119a and the small diameter recess 119b are formed concentrically. In the tray 9, the large diameter recess 119a supports an ingot with a relatively large diameter (for example, a diameter of 6 inches), and the small diameter recess 119b supports an ingot with a relatively small diameter (for example, a diameter of 5 inches).

[0034] Although detailed illustration is omitted, the wafer support portion 118 has a recess 120 corresponding to two or more sizes of wafers. The recess 120 of the wafer support portion 118 may have a configuration having a ring-shaped large-diameter recess recessed downward from the upper surface of the lower wall 114, and a circular small-diameter recess having a smaller diameter than the large-diameter recess and recessed further downward than the large-diameter recess, similar to the configuration of the recess 119 of the ingot support portion 117. The large-diameter recess and the small-diameter recess of the wafer support portion 118 may be formed concentrically. In the tray 9, the large-diameter recess of the wafer support portion 118 supports a wafer having a relatively large diameter (for example, a diameter of 6 inches), and the small-diameter recess of the wafer support portion 118 supports a wafer having a relatively small diameter (for example, a diameter of 5 inches). Contrary to the embodiment shown in the drawings, the tray 9 may have a configuration having a wafer support portion on the upper surface of the upper wall 113 and an ingot support portion on the upper surface of the lower wall 114.

[0035] The belt conveyor unit 10 will be described with reference to Fig. 9. The belt conveyor unit 10, which is arranged along the ingot grinding unit 4, the laser irradiation unit 6, and the wafer separation unit 8, is composed of at least an outgoing belt conveyor 121 that conveys the tray 9 in the Y1 direction indicated by the arrow Y1 in Fig. 9, a return belt conveyor 122 that conveys the tray 9 in the Y2 direction (opposite to Y1) indicated by the arrow Y2 in Fig. 9, and a conveying means 123 that conveys the tray 9 from the end point of the outgoing belt conveyor 121 to the start point of the return belt conveyor 122.

[0036] The outgoing belt conveyor 121 includes a pair of support walls 125 extending in the Y-axis direction at an interval in the X-axis direction, a plurality of rollers 126 rotatably mounted on the inner surface of each support wall 125 at an interval in the Y-axis direction, a pair of endless belts 127 wound around the rollers 126, and a motor 128 for rotating the rollers 126. In the illustrated embodiment, three outgoing belt conveyors 121 are arranged along the Y-axis direction, but the length of the conveying path for the trays 9 can be changed by appropriately changing the number of outgoing belt conveyors 121 and the length of the support walls 125 in the Y-axis direction. In the outgoing belt conveyor 121, the endless belt 127 is rotated by the motor 128 via the rollers 126 to convey the trays 9 mounted on the endless belt 127 in the Y1 direction.

[0037] In the illustrated embodiment, as shown in FIG. 9, the configuration of the return belt conveyor 122 disposed below the forward belt conveyor 121 may be substantially the same as that of the forward belt conveyor 121, and therefore the configuration of the return belt conveyor 122 is given the same reference numeral as that of the forward belt conveyor 121. In the return belt conveyor 122, the endless belt 127 is rotated by a motor 128 via a roller 126 in the opposite direction to that of the forward belt conveyor 121, so that the tray 9 mounted on the endless belt 127 is transported in the Y2 direction. The return belt conveyor 122 may be disposed above the forward belt conveyor 121. In addition, when the wafer generating apparatus 2 is in operation, it is preferable that both the forward belt conveyor 121 and the return belt conveyor 122 are in operation at all times.

[0038] 9, trace stoppers 129 for stopping the trays 9 being transported by the outbound belt conveyor 121 are disposed at positions on the outbound belt conveyor 121 facing the ingot grinding unit 4 and at positions facing the laser irradiation unit 6. In the illustrated embodiment, as shown in FIG 10, the trace stoppers 129 include a base plate 130 fixed by an appropriate bracket (not shown), a lifting plate 131 supported on the upper surface of the base plate 130 so as to be able to rise and fall freely, a cylinder means 132 for lifting and lowering the lifting plate 131, and a stopper piece 133 fixed to the downstream end of the lifting plate 131 in the Y1 direction.

[0039] 10, a pair of engaging projections 131a are formed on the upper surface of the lift plate 131 to engage with a pair of engaged recesses (not shown) formed on the lower surface of the lower wall 114 of the tray 9. As shown in Fig. 10 and Fig. 11, the air-driven or electrically-driven cylinder means 132 positions the lift plate 131 at a passing position (e.g., the position shown in Fig. 10(a) and Fig. 11(a)) where the upper end of the stopper piece 133 is located lower than the lower end of the tray 9 being transported by the outgoing belt conveyor 121, a stopping position (e.g., the position shown in Fig. 10(b) and Fig. 11(b)) where the stopper piece 133 comes into contact with the tray 9 being transported by the outgoing belt conveyor 121, and a separating position (e.g., the position shown in Fig. 10(c) and Fig. 11(c)) where the tray 9 is separated from the endless belt 127.

[0040] In the trace stopper 129, the lift plate 131 is positioned at a passing position to allow the tray 9 to pass above the trace stopper 129 (see FIG. 11(a)). Also, the lift plate 131 is positioned at a stop position above the passing position to stop the tray 9 being transported by the forward belt conveyor 121 (see FIG. 11(b)). Furthermore, in the trace stopper 129, the lift plate 131 is positioned at a separation position above the stop position to prevent the load on the motor 128 of the forward belt conveyor 121 from increasing due to the sliding between the lower surface of the stopped tray 9 and the upper surface of the endless belt 127 (see FIG. 11(c)). Also, when the engaging protrusion 131a of the lift plate 131 engages with the engaging recess of the tray 9 at the stop position or separation position, the positional deviation of the tray 9 on the lift plate 131 is prevented.

[0041] The conveying means 123 will be described with reference to Figures 9 and 12. The conveying means 123, which is disposed adjacent to the end point of the outgoing belt conveyor 121 and the start point of the return belt conveyor 122, includes a support wall 134 extending in the Z-axis direction, a lifting plate 135 supported on the support wall 134 so as to be freely raised and lowered, a lifting means 136 for lifting and lowering the lifting plate 135, a Y-axis movable plate 137 supported on the upper surface of the lifting plate 135 so as to be freely movable in the Y-axis direction, a Y-axis feed means (not shown) for moving the Y-axis movable plate 137 in the Y-axis direction, and a stopper piece 138 fixed to the downstream end of the Y-axis movable plate 137 in the Y1 direction.

[0042] The lifting means 136 has a ball screw 139 connected to the lifting plate 135 and extending in the Z-axis direction, and a motor 140 for rotating the ball screw 139, and moves the lifting plate 135 along the guide rail 134a of the support wall 134 between the raised position shown in FIG. 12(a) and the lowered position shown in FIG. 12(b) in the Z-axis direction and stops it at any position. A pair of engagement protrusions 137a that engage with the pair of engaged recesses of the tray 9 is formed on the upper surface of the Y-axis movable plate 137. The Y-axis feed means is composed of, for example, an air cylinder or an electric cylinder, and moves the Y-axis movable plate 137 along the guide rail 135a of the lifting plate 135 in the Y-axis direction between the forward position shown by the two-dot chain line in FIG. 12(a) and FIG. 12(b) and the retreated position shown by the solid line in FIG. 12(a) and FIG. 12(b).

[0043] In the conveying means 123, the upper surface of the Y-axis movable plate 137 is positioned slightly below the upper surface of the endless belt 127 of the forward belt conveyor 121, and the Y-axis movable plate 137 is positioned at the forward position, so that the stopper piece 138 comes into contact with the tray 9 being conveyed by the forward belt conveyor 121, and the tray 9 can be stopped at the end point of the forward belt conveyor 121 (which is also the position facing the wafer peeling unit 8 in the illustrated embodiment). In addition, by raising the lift plate 135 in a state where the tray 9 is stopped, the lower surface of the tray 9 is separated from the upper surface of the endless belt 127, and the tray 9 can be mounted on the upper surface of the Y-axis movable plate 137. When the tray 9 is mounted on the Y-axis movable plate 137, the engaging protrusion 137a of the Y-axis movable plate 137 engages with the engaging recess of the tray 9, and the positional deviation of the tray 9 on the Y-axis movable plate 137 is prevented. Furthermore, the Y-axis movable plate 137 carrying the tray 9 is positioned at the retracted position, then the lift plate 135 is lowered until the upper surface of the Y-axis movable plate 137 is positioned slightly above the upper surface of the endless belt 127 of the return belt conveyor 122, and then the Y-axis movable plate 137 is positioned at the forward position and the lift plate 135 is lowered slightly, thereby transferring the tray 9 from the Y-axis movable plate 137 to the endless belt 127 of the return belt conveyor 122. In this manner, the transport means 123 transports the tray 9 from the end point of the outgoing belt conveyor 121 to the start point of the return belt conveyor 122.

[0044] In the illustrated embodiment, as shown in FIG. 9, the belt conveyor unit 10 further includes a first transfer means 141 for transferring ingots between the tray 9 stopped by the trace stopper 129 on the starting side of the outbound belt conveyor 121 and the ingot grinding unit 4, a second transfer means 142 for transferring ingots between the tray 9 stopped by the trace stopper 129 on the ending side of the outbound belt conveyor 121 and the laser irradiation unit 6, and a third transfer means 143 for transferring ingots between the tray 9 stopped by the transport means 123 and the wafer peeling unit 8 and transferring wafers peeled off from the ingots from the wafer peeling unit 8 to the tray 9.

[0045] Since the configuration of the second transfer means 142 and the configuration of the third transfer means 143 may be the same as that of the first transfer means 141, the configuration of the first transfer means 141 will be described below, and the configurations of the second transfer means 142 and the third transfer means 143 will not be described. The first transfer means 141 includes a multi-joint arm 144, a drive source (not shown) for driving the multi-joint arm 144, and a U-shaped suction piece 145 attached to the tip of the multi-joint arm 144. The drive source, which is an air drive source or an electric drive source, drives the multi-joint arm 144 to position the suction piece 145 at any position in each of the X-axis direction, the Y-axis direction, and the Z-axis direction, and also to turn the suction piece 145 upside down. The suction piece 145, which has a plurality of suction holes (not shown) formed on one side, is connected to a suction means (not shown), and in the first transferring means 141, the suction means generates a suction force on the suction piece 145, thereby suction-holding the ingot with the suction piece 145. In the first transferring means 141, the articulated arm 144 is driven by a driving source to transfer the ingot sucked by the suction piece 145 between the tray 9 stopped by the trace stopper 129 and the ingot grinding unit 4. The suction piece 145 of the first and second transferring means 141, 142 does not have to be U-shaped and may be, for example, disk-shaped.

[0046] The ingot stocker 11 will be described with reference to Fig. 13. The ingot stocker 11 in the illustrated embodiment is at least composed of a placement table 146 on which trays 9 supporting ingots are placed, a first endless belt 148 disposed on the placement table 146 and feeding out the trays 9 supporting the ingots, a driving force transmission section 150 connected to the first endless belt 148 and transmitting a driving force, and a rack 152 on which a plurality of placement tables 146 are disposed above and below.

[0047] 13, a rectangular opening 154 extending in the Y-axis direction is formed on the upper surface of the rectangular mounting table 146, and a plurality of rollers (not shown) are rotatably mounted on the mounting table 146. A first endless belt 148 is wound around the plurality of rollers of the mounting table 146, and the upper surface of the first endless belt 148 is exposed from the rectangular opening 154. A cylindrical driving force transmission unit 150 extending in the X-axis direction is rotatably mounted on the mounting table 146. One end of the driving force transmission unit 150 protrudes from a side surface on one end side of the mounting table 146 in the Y-axis direction, and the other end of the driving force transmission unit 150 is connected to the rollers around which the first endless belt 148 is wound. The rack 152 in the illustrated embodiment includes a pair of side panels 156 spaced apart in the X-axis direction, and four shelves 158 spaced apart in the vertical direction between the side panels 156, with a loading table 146 provided on each shelf 158. In the ingot stocker 11, when the driving force transmission unit 150 rotates, the first endless belt 148 rotates, and the tray 9 placed on the upper surface of the loading table 146 is sent out in the Y-axis direction by the first endless belt 148. The roller of the loading table 146 may be made of a cylindrical member and may also serve as the driving force transmission unit 150.

[0048] The ingot delivery unit 12 will be described with reference to Figures 1 and 14. As shown in Figure 1, the ingot delivery unit 12 is disposed between the belt conveyor unit 10 and the ingot stocker 11. As shown in Figure 14, the ingot delivery unit 12 of the illustrated embodiment is at least composed of a receiving table 160 that receives the tray 9 supporting the ingot from the placement table 146, a second endless belt 162 that is disposed on the receiving table 160 and transfers the tray 9 supporting the ingot to the belt conveyor unit 10, a motor 164 that drives the second endless belt 162, a clutch unit 166 that is connected to the second endless belt 162 and transmits the driving force to the driving force transmission unit 150 of the ingot stocker 11, and an elevator 168 that positions the receiving table 160 on the placement tables 146 that are disposed above and below.

[0049] As shown in FIG. 14, a pair of rectangular openings 170 extending in the Y-axis direction are formed at an interval in the X-axis direction on the upper surface of the rectangular receiving table 160, and a plurality of rollers (not shown) are rotatably mounted on the receiving table 160. A second endless belt 162 is wound around the plurality of rollers of the receiving table 160, and the upper surface of the second endless belt 162 is exposed from the rectangular opening 170. A cylindrical driving force transmission unit 172 extending in the X-axis direction is rotatably mounted on one end side of the receiving table 160 in the Y-axis direction. One end of the driving force transmission unit 172 protrudes from the side surface of the receiving table 160, and the other end of the driving force transmission unit 172 is connected to the roller around which the second endless belt 162 is wound. A motor 164 is mounted on the side surface of the other end side of the receiving table 160 in the Y-axis direction, and a rotation shaft (not shown) of the motor 164 is connected to the roller around which the second endless belt 162 is wound. The rollers of the receiving table 160 may be made of cylindrical members and may also serve as the driving force transmission unit 172 .

[0050] 14, the clutch unit 166 includes an air cylinder 174 having a cylinder tube 174a fixed to the receiving table 160 and a piston rod 174b attached to the cylinder tube 174a so as to be movable forward and backward in the X-axis direction, a bracket piece 176 fixed to the tip of the piston rod 174b of the air cylinder 174, a pair of tapered pins 178 rotatably attached to the bracket piece 176 at a distance in the Y-axis direction, and an endless transmission belt 180 wound around the pair of tapered pins 178. The elevator 168 includes a base plate 182, a support plate 184 extending in the Z-axis direction from one end of the base plate 182 in the X-axis direction, a lift plate 186 supported by the support plate 184 so as to be liftable, and a lifting means 188 for lifting the lift plate 186. The receiving table 160 is disposed on the upper surface of the lift plate 186. The lifting means 188 has a ball screw (not shown) connected to the lifting plate 186 and extending in the Z-axis direction, and a motor 190 that rotates this ball screw, and is configured to raise and lower the lifting plate 186 in the Z-axis direction along the guide rail 184a of the support plate 184 and stop it at any position.

[0051] Explaining with reference to Fig. 15, in the ingot delivery unit 12, the lift plate 186 of the elevator 168 is raised and lowered, and the lift plate 186 is stopped at a position where the upper surface of any of the placement tables 146 of the ingot stocker 11 coincides with the upper surface of the receiving table 160, and then the piston rod 174b of the air cylinder 174 of the clutch part 166 is moved from the extended position to the retracted position shown in Fig. 15. Then, one of the pair of taper pins 178 of the clutch part 166 is inserted into the driving force transmission part 150 of the ingot stocker 11 and connected so as to be able to transmit rotation, and the other of the pair of taper pins 178 is inserted into the driving force transmission part 172 of the ingot delivery unit 12 and connected so as to be able to transmit rotation. In this state, when the motor 164 rotates, the second endless belt 162 rotates, and the driving force transmission section 172 of the ingot delivery unit 12, the pair of taper pins 178, the transmission belt 180, and the driving force transmission section 150 of the ingot stocker 11 rotate, causing the first endless belt 148 of the ingot stocker 11 to rotate. As a result, the tray 9 placed on the upper surface of the placement table 146 of the ingot stocker 11 is sent out in the Y-axis direction by the first endless belt 148 and delivered to the receiving table 160 of the ingot delivery unit 12.

[0052] After the ingot delivery unit 12 receives the tray 9 on the receiving table 160, the ingot delivery unit 12 stops the rotation of the motor 164 and moves the piston rod 174b of the air cylinder 174 of the clutch section 166 from the retracted position to the extended position, thereby releasing the connection between one of the pair of taper pins 178 and the driving force transmission section 150 of the ingot stocker 11 and releasing the connection between the other of the pair of taper pins 178 and the driving force transmission section 172 of the ingot delivery unit 12. Then, the ingot delivery unit 12 rotates the motor 164 after appropriately raising and lowering the lift plate 186 with the elevator 168 to align the upper surface of the receiving table 160 on which the tray 9 is placed with the upper surface of the endless belt 127 of the outgoing belt conveyor 121 of the belt conveyor unit 10. This rotates the second endless belt 162, and the tray 9 placed on the upper surface of the receiving table 160 is delivered to the outgoing belt conveyor 121 of the belt conveyor unit 10. In this manner, the ingot delivery unit 12 delivers the ingots supported on the tray 9 contained in the ingot stocker 11 to the belt conveyor unit 10.

[0053] The driving force transmission section 150 of the ingot stocker 11, the driving force transmission section 172 of the ingot delivery unit 12, and the clutch section 166 are not limited to the above-mentioned embodiment, and may be another embodiment as shown in Fig. 16. In the other embodiment shown in Fig. 16, instead of the pair of taper pins 178 of the above-mentioned clutch section 166, a rotating shaft 192 connected to the rollers of the receiving table 160 and a driving magnet member 194 are rotatably attached to the bracket piece 176. In addition, a driven magnet member 196 is attached to the rollers of the placement table 146 as a driving force transmission section.

[0054] 16, after the lift plate 186 is moved to a position where the upper surface of any of the placement tables 146 of the ingot stocker 11 coincides with the upper surface of the receiving table 160, the rotation of the motor 164 is transmitted to the first endless belt 148 of the placement table 146 via a magnetic coupling consisting of a driving magnet member 194 and a driven magnet member 196. Note that since the magnetic coupling may be non-contact (a gap can be provided between the driving magnet member 194 and the driven magnet member 196), the air cylinder 174 for moving the bracket piece 176 in the X-axis direction is not required in the other embodiment shown in FIG.

[0055] Referring to Figures 1 and 9, the wafer generation apparatus 2 of the illustrated embodiment further includes a cassette stocker 200 that houses a plurality of cassettes 198 for housing peeled wafers, and a storage means 202 that stores wafers supported by the wafer support portions 118 of the trays 9 in the cassettes 198 housed in the cassette stocker 200.

[0056] As shown in Fig. 1, the cassette stocker 200 has a total of 16 cassette accommodating sections 204 arranged in four rows in the X-axis direction and four stages in the Z-axis direction. Each cassette accommodating section 204 accommodates a cassette 198 that accommodates wafers peeled off from an ingot in the wafer peeling unit 8. The cassette 198 can accommodate a plurality of wafers (e.g., 25 wafers) at intervals in the vertical direction. In the cassette stocker 200, each cassette accommodating section 204 penetrates in the Y-axis direction, and the cassette 198 can be accommodated in each cassette accommodating section 204 from the front side in the Y-axis direction in Fig. 1, and the wafers can be accommodated in the cassette 198 in the cassette accommodating section 204 from the rear side in the Y-axis direction in Fig. 1.

[0057] 9, the storage means 202 is disposed adjacent to the ingot delivery unit 12 and the cassette stocker 200. The storage means 202 includes a support wall 206, an X-axis movable member 208 supported by the support wall 206 so as to be movable in the X-axis direction, an X-axis feed means 210 for moving the X-axis movable member 208 in the X-axis direction, a lifting block 212 supported by the X-axis movable member 208 so as to be liftable and lowerable, a lifting means 214 for lifting and lowering the lifting block 212, a multi-joint arm 216 supported by the lifting block 212, a holding piece 218 attached to the tip of the multi-joint arm 216 so as to be capable of being turned upside down, and a drive source (not shown) for driving the multi-joint arm 216.

[0058] Continuing the explanation with reference to Fig. 9, X-axis feed means 210 supported by support wall 206 has ball screw 220, the nut part 220a of which is fixed to X-axis movable member 208 and extends in the X-axis direction, and motor 222 for rotating ball screw 220, and moves X-axis movable member 208 in the X-axis direction along guide rail 206a of support wall 206. Elevation means 214 supported by X-axis movable member 208 has ball screw 224 connected to elevating block 212 and extends in the Z-axis direction, and motor 226 for rotating ball screw 224, and elevates elevating block 212 along guide rail 208a of X-axis movable member 208. A drive source consisting of an air drive source or an electric drive source drives multi-joint arm 216 to position holding piece 218 at any position in each of the X-axis, Y-axis, and Z-axis directions, and also turns holding piece 218 upside down. The holding piece 218, which has a plurality of suction holes (not shown) formed on one side, is connected to a suction means (not shown).

[0059] In the storage means 202, the suction holes of the holding piece 218 are directed downward, and a suction force is generated in the holding piece 218 by the suction means, so that the wafer supported by the wafer support portion 118 of the tray 9 can be held by the holding piece 218 through suction, and the wafer held by the holding piece 218 can be stored in the cassette 198 contained in the cassette stocker 200.

[0060] The quality inspection unit 13 will be described with reference to Figures 1, 17 and 18. As shown in Figure 1, the quality inspection unit 13 in the illustrated embodiment includes an ingot quality inspection unit 300 that inspects the quality of an ingot, and a wafer quality inspection unit 302 that inspects the quality of a wafer peeled from the ingot.

[0061] 1, the ingot quality inspection unit 300 is disposed above the outbound belt conveyor 121, between the trace stopper 129 disposed at a position facing the ingot grinding unit 4 and the trace stopper 129 disposed at a position facing the laser irradiation unit 6. Referring to FIG. 17, the ingot quality inspection unit 300 includes an illuminator 304, an imaging means 308 that receives reflected light 306b (see FIG. 17(b)) of light 306a (see FIG. 17(b)) from the illuminator 304 reflected on the top surface of the ingot, and an ingot defect detection means 310 that processes the image captured by the imaging means 308 and detects defects.

[0062] The illuminator 304 and the imaging means 308 are disposed at an interval in the conveying direction (Y1 direction) of the outbound belt conveyor 121, and are supported by an appropriate bracket (not shown). The light 306a of the illuminator 304 may be visible light. The imaging means 308 may be a line sensor in which multiple imaging elements are arranged in a line.

[0063] 17(b), the angle θ1 (incident angle θ1) between the light 306a of the illuminator 304 and the normal 312 to the top surface of the ingot is preferably an angle at which total reflection occurs. However, the incident angle θ1 may be an angle at which a part of the light 306a of the illuminator 304 is reflected by the top surface of the ingot and defects on the top surface of the ingot can be imaged by the imaging means 308.

[0064] The ingot defect detection means 310 in the illustrated embodiment is configured as a part of the control means 314 (computer) that controls the operation of the wafer generating apparatus 2. The control means 314 is electrically connected to the imaging means 308, and the data of the image captured by the imaging means 308 is input to the ingot defect detection means 310 of the control means 314. The ingot defect detection means 310 processes the image captured by the imaging means 308 and detects defects on the top surface of the ingot that may hinder the incidence of the laser beam LB of the laser irradiation unit 6. An example of a defect on the top surface of the ingot is a linear scratch 316 (see FIG. 17(c)) formed on the top surface of the ingot due to peeling off the wafer from the ingot.

[0065] In the illustrated embodiment, the wafer generating apparatus 2 is provided with a single ingot quality inspection unit 300, but may be provided with a first ingot quality inspection unit for inspecting the quality of an ingot roughly ground by an ingot grinding unit for rough grinding, and a second ingot quality inspection unit for inspecting the quality of an ingot finish ground by an ingot grinding unit for finish grinding. The configuration of the first and second ingot quality inspection units may be the same as that of the ingot quality inspection unit 300 described above.

[0066] 1, the wafer quality inspection unit 302 is disposed adjacent to the downstream end in the Y1 direction of the outbound belt conveyor 121 and the wafer separation unit 8. Explaining with reference to Fig. 18, the wafer quality inspection unit 302 includes an illuminator 318, an imaging means 322 that receives reflected light 320b (see Fig. 18(b)) of light 320a (see Fig. 18(b)) from the illuminator 318 reflected on the upper surface of the wafer, a wafer defect detection means 324 that processes the image captured by the imaging means 322 and detects defects, and a wafer belt conveyor 326 that moves the wafer when the wafer is imaged by the imaging means 322.

[0067] The illuminator 318 and the imaging means 322 are arranged at an interval in the transport direction of the wafer belt conveyor 326 (Y-axis direction in the illustrated embodiment) and are supported by an appropriate bracket (not shown). The light 320a of the illuminator 318 may be visible light. The imaging means 322 may be a line sensor in which a number of imaging elements are arranged in a line. The angle θ2 (incident angle θ2) between the light 320a of the illuminator 318 and a normal 328 to the upper surface of the wafer is set to an angle at which substantially total reflection occurs. The wafer belt conveyor 326 is designed so that the transport direction can be switched between the Y1 direction and the Y2 direction.

[0068] The wafer defect detection means 324 in the illustrated embodiment is configured as a part of the control means 314, similar to the ingot defect detection means 310, and image data captured by the imaging means 322 is input to the wafer defect detection means 324. The wafer defect detection means 324 processes the image captured by the imaging means 322 and detects defects on the upper surface of the wafer, such as a crack 330 as shown in Fig. 18(c).

[0069] 19(a) to (c) show an ingot 230 that can be processed by the wafer generation apparatus 2. The ingot 230 shown in the figure is formed from hexagonal single crystal SiC in an overall cylindrical shape, and has a circular first surface 232, a circular second surface 234 opposite the first surface 232, a peripheral surface 236 located between the first surface 232 and the second surface 234, and a c-axis ( <0001> The crystal has a c-plane ({0001} plane) perpendicular to the c-axis.

[0070] In the illustrated ingot 230, the c-axis is inclined with respect to a perpendicular line 238 of the first surface 232, and an off angle α (for example, α=1, 3, or 6 degrees) is formed between the c-plane and the first surface 232. The direction in which the off angle α is formed is indicated by an arrow A in FIGS. 19(a) to 19(c). In addition, a rectangular first orientation flat 240 and a second orientation flat 242 indicating the crystal orientation are formed on the peripheral surface 236 of the ingot 230. The first orientation flat 240 is parallel to the direction A in which the off angle α is formed, and the second orientation flat 242 is perpendicular to the direction A in which the off angle α is formed. As shown in FIG. 19(b), when viewed from above, the length L2 of the second orientation flat 242 is shorter than the length L1 of the first orientation flat 240 (L2 <L1)。

[0071] The ingot that can be processed by the wafer generating apparatus 2 is not limited to the ingot 230 described above, and may be, for example, a single crystal SiC ingot whose c-axis is not inclined with respect to the perpendicular line to the first surface and whose off-angle between the c-plane and the first surface is 0 degrees (i.e., the perpendicular line to the first surface and the c-axis coincide), or an ingot formed from a material other than single crystal SiC, such as Si (silicon) or GaN (gallium nitride).

[0072] When producing wafers from the ingot 230 by the wafer producing apparatus 2 as described above, first, an ingot accommodation step is performed in which the ingot 230 is accommodated in the ingot stocker 11. In the ingot accommodation step of the illustrated embodiment, first, four ingots 230 are prepared, and as shown in Fig. 1, the four ingots 230 are supported by the ingot support parts 117 of the four trays 9. Next, each tray 9 supporting the ingot 230 is placed on each mounting table 146 of the ingot stocker 11 and accommodated.

[0073] After the ingot accommodation step is performed, a first transport step of transporting the ingot 230 from the ingot stocker 11 to the laser irradiation unit 6 is performed by the ingot delivery unit 12 and the belt conveyor unit 10. Since the end faces (first face 232 and second face 234) of the ingot 230 are usually flattened to such an extent that they do not prevent the incidence of the laser beam in the peeling layer formation step described later, in the illustrated embodiment, an example of transporting the ingot 230 from the ingot stocker 11 to the laser irradiation unit 6 in the first transport step is described, but if the end faces of the ingot 230 are not flattened to such an extent that they do not prevent the incidence of the laser beam in the peeling layer formation step, the ingot 230 may be transported from the ingot stocker 11 to the ingot grinding unit 4 in the first transport step.

[0074] In the first transport step, first, the lift plate 186 of the elevator 168 of the ingot delivery unit 12 is raised and lowered to position the lift plate 186 at a position where the upper surface of the placement table 146 at an arbitrary position (for example, the top stage) of the ingot stocker 11 coincides with the upper surface of the receiving table 160. Next, the air cylinder 174 of the clutch part 166 is operated to insert one of the pair of taper pins 178 of the clutch part 166 into the driving force transmission part 150 of the ingot stocker 11, and the other of the pair of taper pins 178 into the driving force transmission part 172 of the ingot delivery unit 12. Next, the motor 164 of the ingot delivery unit 12 is rotated to rotate the first endless belt 148 together with the second endless belt 162. As a result, the tray 9 placed on the placement table 146 is sent out in the Y-axis direction by the first endless belt 148 and delivered to the receiving table 160 of the ingot delivery unit 12.

[0075] After the tray 9 is delivered to the receiving table 160, the rotation of the motor 164 is stopped. In addition, the piston rod 174b of the air cylinder 174 is moved from the retracted position to the extended position to release the connection between one of the pair of taper pins 178 and the driving force transmission part 150 of the ingot stocker 11, and release the connection between the other of the pair of taper pins 178 and the driving force transmission part 172 of the ingot delivery unit 12. Next, the lift plate 186 of the elevator 168 is moved to make the upper surface of the receiving table 160 on which the tray 9 is placed coincide with the upper surface of the endless belt 127 of the forward belt conveyor 121 of the belt conveyor unit 10. Next, the motor 164 is rotated to rotate the second endless belt 162, and the tray 9 placed on the upper surface of the receiving table 160 is delivered to the forward belt conveyor 121.

[0076] After the tray 9 is handed over to the outgoing belt conveyor 121, the tray 9 is transported by the outgoing belt conveyor 121 to a position facing the laser irradiation unit 6. At this time, the lifting plate 131 of the trace stopper 129 arranged at a position facing the ingot grinding unit 4 is positioned at a passing position, and the lifting plate 131 of the trace stopper 129 arranged at a position facing the laser irradiation unit 6 is positioned at a stopping position. This allows the tray 9 transported in the Y1 direction by the outgoing belt conveyor 121 to pass above the trace stopper 129 arranged at a position facing the ingot grinding unit 4, and to be stopped at the trace stopper 129 at a position facing the laser irradiation unit 6.

[0077] Next, in order to separate the lower surface of the stopped tray 9 from the upper surface of the endless belt 127, the lift plate 131 of the trace stopper 129 is raised to a separation position. Next, the articulated arm 144 of the second transfer means 142 is driven to bring the suction piece 145 into close contact with the upper surface of the ingot 230 (the first surface 232 in the illustrated embodiment). Next, the suction means connected to the suction piece 145 is operated to generate a suction force in the suction piece 145, and the ingot 230 is suction-held by the suction piece 145. Next, the articulated arm 144 moves the suction piece 145, and as shown in FIG. 18, the lower surface (the second surface 234 in the illustrated embodiment) of the ingot 230 suction-held by the suction piece 145 is brought into contact with the upper surface of the second holding table 60 of the laser irradiation unit 6. At this time, the second holding table 60 is positioned at an ingot attachment / detachment position (the position shown in FIG. 4) for attaching and detaching the ingot.

[0078] 20, a first straight portion 66a corresponding to the first orientation flat 240 of the ingot 230 and a second straight portion 66b corresponding to the second orientation flat 242 are formed on the periphery of the circular suction chuck 66 in the illustrated embodiment, so that the ingot 230 on which the first orientation flat 240 and the second orientation flat 242 are formed can be sucked and held by the suction chuck 66 with a predetermined suction force. Then, the suction means connected to the suction piece 145 is stopped, the suction force of the suction piece 145 is released, and the ingot 230 is placed on the upper surface of the second holding table 60. In this manner, the first transport step of transporting the ingot 230 from the ingot stocker 11 to the laser irradiation unit 6 is performed. Although not shown, the suction chuck 22 of the first holding table 14 of the ingot grinding unit 4 and the suction chuck 86 of the third holding table 80 of the wafer peeling unit 8 are also formed with a first straight portion corresponding to the first orientation flat 240 and a second straight portion corresponding to the second orientation flat 242.

[0079] After the first transport step is carried out, the ingot 230 is held on the second holding table 60, and a focusing point of a laser beam having a wavelength that is transparent to the ingot 230 is positioned at a depth corresponding to the thickness of the wafer to be produced from the top surface of the ingot 230 held on the second holding table 60, and a peeling layer formation step is carried out in the laser irradiation unit 6, in which the laser beam is irradiated onto the ingot 230 to form a peeling layer.

[0080] In the peeling layer forming process, first, a suction force is generated on the upper surface of the second holding table 60, and the ingot 230 is held by the second holding table 60 under suction. Next, the second holding table 60 is moved in the X-axis direction by the X-axis feed means, and the Y-axis movable member is moved in the Y-axis direction by the Y-axis feed means, so that the ingot 230 is positioned below the alignment means 76. Next, the alignment means 76 captures an image of the ingot 230 from above the ingot 230. Next, based on the image of the ingot 230 captured by the alignment means 76, the second holding table 60 is rotated and moved by the second holding table motor and the X-axis feed means, and the Y-axis movable member is moved by the Y-axis feed means, thereby adjusting the orientation of the ingot 230 to a predetermined orientation and adjusting the positions of the ingot 230 and the condenser 74 in the XY plane. When adjusting the orientation of the ingot 230 to a predetermined orientation, as shown in FIG. 21(a), the second orientation flat 242 is aligned in the X-axis direction, so that the direction perpendicular to the direction A in which the off angle α is formed is aligned in the X-axis direction, and the direction A in which the off angle α is formed is aligned in the Y-axis direction.

[0081] Next, the condenser 74 is raised and lowered by the condenser position adjustment means, and the condenser FP is positioned at a depth corresponding to the thickness of the wafer to be produced from the first surface 232 of the ingot 230, as shown in Fig. 21(b). Next, while the second holding table 60 is moved by the X-axis feed means in the X-axis direction aligned with the direction perpendicular to the direction A in which the off-angle α is formed, the condenser 74 irradiates the ingot 230 with a pulsed laser beam LB having a wavelength that is transparent to the ingot 230. Then, as shown in Figs. 22(a) and 22(b), the SiC is separated into Si (silicon) and C (carbon) by the irradiation of the pulsed laser beam LB, and the next irradiated pulsed laser beam LB is absorbed by the previously formed C, so that the SiC is separated into Si and C in a chain reaction, and a crack 248 is generated that extends isotropically along the c-plane from a portion 246 where the SiC is separated into Si and C.

[0082] Next, the Y-axis movable member is moved by the Y-axis feed means, so that the focal point FP is index-fed by a predetermined index amount Li relative to the ingot 230 in the Y-axis direction aligned with the direction A in which the off angle α is formed, within a range not exceeding the width of the crack 248. Then, by alternately repeating the irradiation of the pulsed laser beam LB and the index feed, a plurality of separation parts 246 extending continuously in a direction perpendicular to the direction A in which the off angle α is formed are formed at intervals of the predetermined index amount Li in the direction A in which the off angle α is formed, and cracks 248 extending isotropically from the separation parts 246 along the c-plane are sequentially generated so that adjacent cracks 248 overlap each other in the direction A in which the off angle α is formed when viewed in the vertical direction. This allows the separation layer 250, which is made up of the separation parts 246 and the cracks 248 and has reduced strength for peeling the wafer from the ingot 230, to be formed at a depth corresponding to the thickness of the wafer to be generated from the top surface of the ingot 230. After the separation layer 250 is formed, the second holding table 60 is positioned at the ingot attachment / detachment position, and the suction force of the second holding table 60 is released. The separation layer forming step can be performed, for example, under the following processing conditions. Pulsed laser beam wavelength: 1064nm Repetition frequency: 80kHz Average output: 3.2W Pulse width: 4ns Diameter of the focal point: 3μm Condenser lens numerical aperture (NA): 0.43 Z-axis position of focal point: 300 μm from the top surface of the ingot Second holding table feed speed: 120~260mm / s Index amount: 250~400μm

[0083] After the peeling layer forming step is performed, the belt conveyor unit 10 performs a second transport step of transporting the ingot 230 on which the peeling layer 250 has been formed from the laser irradiation unit 6 to the wafer peeling unit 8. In the second transport step, first, the articulated arm 144 of the second transfer means 142 is driven to bring the suction piece 145 into close contact with the first surface 232 of the ingot 230 on the second holding table 60, and the ingot 230 is suction-held by the suction piece 145. Next, the articulated arm 144 moves the suction piece 145, and the second surface 234 of the ingot 230 suction-held by the suction piece 145 is brought into contact with the ingot support portion 117 of the tray 9. Next, the suction force of the suction piece 145 is released, and the ingot 230 is supported by the ingot support portion 117 of the tray 9. Next, the lift plate 131 of the trace stopper 129 is lowered from the separation position to the passing position, thereby placing the tray 9 on the endless belt 127 of the outgoing belt conveyor 121.

[0084] After the tray 9 is placed on the outgoing belt conveyor 121, the tray 9 is transported by the outgoing belt conveyor 121 to a position facing the wafer separation unit 8 (the end point of the outgoing belt conveyor 121 in the illustrated embodiment). At this time, the lift plate 135 is positioned at a height where the upper surface of the Y-axis movable plate 137 of the transport means 123 is lower than the upper surface of the endless belt 127 of the outgoing belt conveyor 121 and the stopper piece 138 comes into contact with the tray 9 being transported by the outgoing belt conveyor 121, and the Y-axis movable plate 137 is positioned at an advanced position. This allows the stopper piece 138 to come into contact with the tray 9 being transported in the Y1 direction by the outgoing belt conveyor 121, and the tray 9 can be stopped at a position facing the wafer separation unit 8.

[0085] Next, the lift plate 135 of the transport means 123 is raised, and the stopped tray 9 is placed on the upper surface of the Y-axis movable plate 137, and the lower surface of the tray 9 is separated from the upper surface of the endless belt 127. Next, the articulated arm 144 of the third transfer means 143 is driven, and the suction piece 145 is brought into close contact with the first surface 232 of the ingot 230, and the ingot 230 is suction-held by the suction piece 145. Next, the articulated arm 144 moves the suction piece 145, and the second surface 234 of the ingot 230 suction-held by the suction piece 145 is brought into contact with the upper surface of the third holding table 80 of the wafer separation unit 8. At this time, the third holding table 80 is positioned at the ingot attachment / detachment position (the position shown in FIG. 6). Then, the suction force of the suction piece 145 is released, and the ingot 230 is placed on the upper surface of the third holding table 80. In this manner, the second transport step of transporting the ingot 230 from the laser irradiation unit 6 to the wafer separation unit 8 is carried out.

[0086] After the second transport step is performed, the ingot 230 on which the delamination layer 250 is formed is held on a third holding table 80, and a wafer delamination step is performed in a wafer delamination unit 8, in which the upper surface of the ingot 230 held on the third holding table 80 is held and the wafer is delaminate- ed from the delamination layer 250.

[0087] In the wafer peeling process, first, the ingot 230 is suction-held by the third holding table 80. Next, as shown in Fig. 23(a), the third holding table 80 is positioned at the wafer peeling position below the liquid tank body 94. Next, the arm 92 is lowered by the arm moving means, and the lower end of the skirt wall 98 of the liquid tank body 94 is brought into close contact with the upper surface of the third holding table 80, as shown in Fig. 23(b).

[0088] 7, the piston rod 108b of the air cylinder 108 is moved to bring the lower surface of the suction piece 112 into close contact with the first surface 232 of the ingot 230. Then, a suction force is generated on the lower surface of the suction piece 112, and the ingot 230 is sucked and held by the suction piece 112 from the first surface 232 side. Then, the liquid supplying means connected to the liquid supplying unit 100 is operated to supply the liquid 106 (e.g., water) from the liquid supplying unit 100 to the liquid containing space 104 until the ultrasonic vibration generating member 110 is immersed. Then, the ultrasonic vibration generating member 110 is operated to apply ultrasonic vibration to the ingot 230, stimulating the peeling layer 250 to extend the crack 248 and further reducing the strength of the peeling layer 250.

[0089] Next, by raising the arm 92 by the arm moving means while the ingot 230 is held by suction with the suction piece 112, the wafer 252 to be produced from the ingot 230 can be peeled from the peeled layer 250 as a starting point, as shown in FIG. 24. When the arm 92 is raised, the liquid 106 is discharged from the liquid storage space 104, and is discharged to the outside of the wafer peeling unit 8 through a drainage port (not shown) formed in the base 84. After the wafer 252 is peeled from the ingot 230, the third holding table 80 is positioned at the ingot attachment / detachment position, and the suction force of the third holding table 80 is released. When ultrasonic vibration is applied to the ingot 230, a gap (for example, 2 to 3 mm) may be provided between the upper surface of the ingot 230 and the lower surface of the suction piece 112. In addition, when peeling the wafer 252 from the ingot 230 starting from the peeling layer 250, the upper surface of the ingot 230 may be suction-held by the suction piece 145 of the third transfer means 143, and then the suction piece 145 may be raised to peel the wafer 252 from the ingot 230.

[0090] After the wafer separation step, a wafer quality inspection step is performed by the wafer quality inspection unit 302 to inspect whether the wafer 252 separated from the ingot 230 has any defects.

[0091] In the wafer quality inspection process, first, the articulated arm 144 of the third transfer means 143 is driven to bring the suction piece 145 of the third transfer means 143 into close contact with the upper surface 252a (flat surface opposite to the uneven peeling surface 252b) of the wafer 252 that is sucked by the suction piece 112 of the wafer peeling means 82, and the wafer 252 is sucked and held by the suction piece 145. Next, the suction force of the suction piece 112 of the wafer peeling means 82 is released, and the wafer 252 is transferred from the suction piece 112 of the wafer peeling means 82 to the suction piece 145 of the third transfer means 143. Next, the suction piece 145 is moved by the articulated arm 144, and the wafer 252 sucked and held by the suction piece 145 is brought into contact with the wafer belt conveyor 326 with the peeling surface 252b of the wafer 252 facing downward. Next, the suction force of the suction piece 145 is released, and the wafer 252 is supported by the wafer belt conveyor 326 .

[0092] 18, while the wafer 252 is being transported by the wafer belt conveyor 326, light 320a from an illuminator 318 is irradiated onto the upper surface 252a of the wafer 252, and reflected light 320b of the light 320a from the illuminator 318 reflected by the upper surface 252a of the wafer 252 is received by the imaging means 322. Then, when the entire upper surface 252a of the wafer 252 is imaged, the wafer belt conveyor 326 is stopped. Then, the image captured by the imaging means 322 is processed, and the wafer defect detection means 324 determines whether or not defects such as cracks 330 exist in the wafer 252.

[0093] If no defect is detected in the wafer 252, the third transport step of transporting the wafer 252 from the wafer quality inspection unit 302 to the cassette 198 of the cassette stocker 200 and storing it therein is performed by the belt conveyor unit 10, the ingot delivery unit 12, and the storage means 202. On the other hand, if a defect is detected in the wafer 252, the wafer 252 in which the defect is detected is discarded. For example, a wafer recovery box (not shown) may be provided at the end of the wafer belt conveyor 326 in the transport direction, and the wafer 252 in which the defect is detected may be transported to the wafer recovery box by the wafer conveyor belt 326 and stored therein. In this way, in the wafer generation apparatus 2 of the illustrated embodiment, the wafer 252 in which the defect is detected is discarded, so that the quality of the wafer 252 to be generated is maintained at a certain level.

[0094] In the third transfer step, first, the articulated arm 144 of the third transfer means 143 is driven to bring the suction piece 145 of the third transfer means 143 into close contact with the upper surface 252a of the wafer 252 on the wafer belt conveyor 326, and the wafer 252 is suction-held by the suction piece 145. Next, the suction force of the suction piece 112 of the wafer peeling means 82 is released, and the wafer 252 is transferred from the suction piece 112 of the wafer peeling means 82 to the suction piece 145 of the third transfer means 143. Next, the articulated arm 144 moves the suction piece 145, and the wafer 252 suction-held by the suction piece 145 is brought into contact with the wafer support portion 118 of the tray 9. Next, the suction force of the suction piece 145 is released, and the wafer 252 is supported by the wafer support portion 118 of the tray 9.

[0095] In the third transport step, the multi-joint arm 144 is driven to transport the wafer 252 and the ingot 230 from which the wafer 252 has been peeled from the wafer peeling unit 8 to the ingot grinding unit 4, and the suction piece 145 is brought into close contact with the peeled surface 230a (see FIG. 24) of the ingot 230 on the third holding table 80, and the ingot 230 is sucked and held by the suction piece 145. Next, the multi-joint arm 144 moves the suction piece 145, and the ingot 230 sucked and held by the suction piece 145 is transported to the ingot support portion 117 of the tray 9 and supported thereon. Next, the Y-axis movable plate 137 of the transport means 123 carrying the tray 9 is positioned at the retreat position. Next, the lift plate 135 is lowered to position the upper surface of the Y-axis movable plate 137 slightly above the upper surface of the endless belt 127 of the return belt conveyor 122. Next, the Y-axis movable plate 137 is positioned at the forward position, and the lift plate 135 is lowered, so that the tray 9 is placed on the endless belt 127 of the return belt conveyor 122.

[0096] After the tray 9 is placed on the return belt conveyor 122, the return belt conveyor 122 transports the tray 9 to its end point. At this time, the elevator 168 of the ingot delivery unit 12 aligns the upper surface of the receiving table 160 with the upper surface of the endless belt 127 of the return belt conveyor 122, and the motor 164 rotates the second endless belt 162 so that the upper surface side of the second endless belt 162 advances in the Y2 direction. As a result, the tray 9 transported in the Y2 direction by the return belt conveyor 122 is placed on the upper surface of the receiving table 160.

[0097] After the tray 9 is placed on the receiving table 160, the rotation of the motor 164 is stopped and the lift plate 186 of the elevator 168 is moved so that the upper surface of the receiving table 160 on which the tray 9 is placed is aligned with the upper surface of the endless belt 127 of the forward belt conveyor 121 of the belt conveyor unit 10. At this time, the piston rod 174b of the air cylinder 174 is positioned at a retracted position so as not to impede the movement of the lift plate 186. Next, the X-axis feed means 210 and the lift means 214 of the storage means 202 move the lift block 212 and drive the articulated arm 216, so that the holding piece 218 is brought into close contact with the upper surface of the wafer 252 supported by the tray 9 on the receiving table 160, and the wafer 252 is suction-held by the holding piece 218. Then, by moving the holding piece 218 by the X-axis feed means 210, the lifting means 214, and the articulated arm 216, the wafer 252 held by suction by the holding piece 218 is carried out from the tray 9 and moved into the cassette 198 of the cassette stocker 200. Then, the suction force of the holding piece 218 is released. In this manner, the wafer 252 peeled off from the ingot 230 is transported from the wafer peeling unit 8 to the cassette 198 of the cassette stocker 200 and stored therein.

[0098] After the wafers 252 are carried out from the tray 9, the second endless belt 162 is rotated to transfer the tray 9 placed on the upper surface of the receiving table 160 to the outgoing belt conveyor 121, and the tray 9 is transported by the outgoing belt conveyor 121. At this time, the lifting plate 131 of the trace stopper 129 arranged at a position facing the ingot grinding unit 4 is positioned at a stop position. This allows the tray 9 being transported in the Y1 direction by the outgoing belt conveyor 121 to be stopped by the trace stopper 129 at a position facing the ingot grinding unit 4.

[0099] Next, in order to separate the lower surface of the stopped tray 9 from the upper surface of the endless belt 127, the lift plate 131 of the trace stopper 129 is raised to the separation position. Next, the articulated arm 144 of the first transfer means 141 is driven to bring the suction piece 145 into close contact with the peeled surface 230a of the ingot 230, and the ingot 230 is sucked and held by the suction piece 145. Next, the articulated arm 144 moves the suction piece 145 to bring the second surface 234 of the ingot 230 into contact with the upper surface of the first holding table 14 of the ingot grinding unit 4, which is positioned at the ingot attachment / detachment position. Then, the suction force of the suction piece 145 is released, and the ingot 230 is placed on the upper surface of the first holding table 14. In this manner, the ingot 230 from which the wafer 252 has been peeled is transported from the wafer peeling unit 8 to the ingot grinding unit 4.

[0100] After the third transport step is performed, the ingot 230 from which the wafer 252 has been peeled is held on the first holding table 14, and an ingot grinding step is performed in the ingot grinding unit 4 to grind and flatten the peeled surface 230a of the ingot 230 held on the first holding table 14.

[0101] Explaining with reference to FIG. 3, in the ingot grinding process, first, a suction force is generated on the upper surface of the first holding table 14, and the ingot 230 is sucked and held by the first holding table 14. Next, the first holding table 14 holding the ingot 230 is positioned at the grinding position. Next, the first holding table 14 holding the ingot 230 is rotated counterclockwise as viewed from above at a predetermined rotation speed (e.g., 300 rpm). Also, the spindle 36 is rotated counterclockwise as viewed from above at a predetermined rotation speed (e.g., 6000 rpm). Next, the spindle housing 30 is lowered, and the grinding wheel 44 is brought into contact with the peeled surface 230a of the ingot 230. Thereafter, the spindle housing 30 is lowered at a predetermined grinding feed speed (e.g., 1.0 μm / s). As a result, the peeled surface 230a of the ingot 230 from which the wafer 252 has been peeled can be ground, and the peeled surface 230a of the ingot 230 can be flattened to an extent that does not prevent the incidence of the pulsed laser beam LB in the peeling layer forming step. After the peeled surface 230a of the ingot 230 has been flattened, the first holding table 14 holding the ingot 230 is positioned at the ingot attachment / detachment position, and the suction force of the first holding table 14 is released.

[0102] After the ingot grinding process, an ingot quality inspection process is performed by the ingot quality inspection unit 300 to inspect whether there are any defects on the peeled surface 230a (upper surface of the ingot 230) of the ingot 230 that would prevent the laser beam from being incident in the peeled layer formation process.

[0103] In the ingot quality inspection process, first, the articulated arm 144 of the first transferring means 141 is driven to bring the suction piece 145 into close contact with the peeled surface 230a of the ingot 230 on the first holding table 14, and the ingot 230 is suction-held by the suction piece 145. Next, the articulated arm 144 moves the suction piece 145, and the second surface 234 of the ingot 230 suction-held by the suction piece 145 is brought into contact with the ingot support portion 117 of the tray 9. Next, the suction force of the suction piece 145 is released, and the ingot 230 is supported by the ingot support portion 117 of the tray 9. Next, the lift plate 131 of the trace stopper 129 is lowered from the separation position to the passing position, so that the tray 9 is placed on the endless belt 127 of the outbound belt conveyor 121.

[0104] 17, while the tray 9 is being transported by the outbound belt conveyor 121, the light 306a from the illuminator 304 is irradiated onto the peeled surface 230a (upper surface of the ingot 230) of the flattened ingot 230, and the light 306a from the illuminator 304 is reflected by the peeled surface 230a and the reflected light 306b is received by the imaging means 308. In this way, the entire peeled surface 230a of the ingot 230 is imaged. Then, the image captured by the imaging means 308 is processed, and the ingot defect detection means 310 determines whether or not there is a defect in the peeled surface 230a of the ingot 230 that would prevent the formation of a required peeled layer.

[0105] If no defect is detected by the ingot defect detection means 310, the ingot 230 in which no defect is detected is subjected to the peeling layer forming step, the wafer peeling step, and the ingot grinding step as described above in sequence. On the other hand, if it is determined that the peeling surface 230a of the ingot 230 is not sufficiently flattened and that a defect that will prevent the laser beam LB from being incident in the peeling layer forming step is present on the peeling surface 230a of the ingot 230, the peeling layer forming step and the wafer peeling step are not performed on the ingot 230 in which the defect is detected, and the ingot 230 in which the defect is detected is transported to the ingot grinding unit 4 by the belt conveyor unit 10 and the ingot transfer unit 12, where the ingot grinding step is performed again, and then the ingot quality inspection step is performed.

[0106] In this manner, in the illustrated embodiment of the wafer generation apparatus 2, the peeling layer formation process and the wafer peeling process are not performed on the ingot 230 in which a defect has been detected, so that the focal point FP of the laser beam LB is not focused at an appropriate position inside the ingot 230, and the required peeling layer is not formed inside the ingot 230, thereby preventing the occurrence of defects in the wafer 252 peeled off from the ingot 230.

[0107] In addition, when an ingot grinding unit for rough grinding and an ingot grinding unit for finish grinding are provided, a first ingot quality inspection unit may inspect whether the surface roughness of the peeled surface 230a of the roughly ground ingot 230 has reached a predetermined surface roughness, and a second ingot quality inspection unit may inspect whether there are any defects on the peeled surface 230a of the finish ground ingot 230 that would prevent the laser beam from being incident in the peeled layer formation process.

[0108] Then, by repeatedly performing the peeling layer formation process, the wafer peeling process, the wafer quality inspection process, the ingot grinding process, and the ingot quality inspection process, the possible number of wafers 252 are produced from the ingot 230, and the wafers 252 are stored in the cassettes 198 of the cassette stocker 200.

[0109] In the illustrated embodiment described above, each process performed on the ingot 230 in the wafer generation apparatus 2 has been described with a focus on one ingot 230. However, in the wafer generation apparatus 2, after performing a first transport process of transporting the ingot 230 from the ingot stocker 11 to the laser irradiation unit 6, the first transport process is repeatedly performed at appropriate intervals, and a peeling layer formation process, a wafer peeling process, an ingot grinding process, and an ingot quality inspection process are repeatedly performed in parallel on multiple ingots 230 (four in the illustrated embodiment), and a wafer quality inspection process is performed on the wafers 252 peeled off from each ingot 230, thereby making it possible to produce as many wafers 252 as possible from multiple ingots 230.

[0110] As described above, the wafer production apparatus 2 in the illustrated embodiment includes the ingot quality inspection unit 300 and the wafer quality inspection unit 302, and therefore can prevent deterioration in the quality of the wafers 252 produced from the ingots 230.

[0111] In the illustrated embodiment, a preferred example in which both the ingot quality inspection unit 300 and the wafer quality inspection unit 302 are provided has been described, but it is sufficient if either the ingot quality inspection unit 300 or the wafer quality inspection unit 302 is provided. [Explanation of symbols]

[0112] 2: Wafer preparation equipment 4: Ingot grinding unit 6: Laser irradiation unit 8: Wafer peeling unit 9: Tray 10: Belt conveyor unit 13: Quality Inspection Unit 14: First holding table 16: Grinding means 60: Second holding table 62: Laser irradiation means 80: Third holding table 82: Wafer peeling means 117: Ingot support 118: Wafer support 230: Ingot 250: peeling layer 252: Wafer

Claims

1. A wafer producing apparatus for producing wafers from an ingot, comprising: an ingot grinding unit including at least a first holding table for holding an ingot and a grinding means for grinding and flattening an upper surface of the ingot held on the first holding table; a laser irradiation unit including at least a second holding table for holding an ingot and a laser irradiation means for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of a wafer to be produced from an upper surface of the ingot held on the second holding table, and irradiating the ingot with the laser beam to form a peeling layer; a wafer separation unit including at least a third holding table for holding an ingot and a wafer separation means for holding an upper surface of the ingot held on the third holding table and separating the wafer from the separation layer; a tray having an ingot support portion for supporting an ingot and a wafer support portion for supporting a peeled wafer; a belt conveyor unit for transporting the ingots supported on the tray between the ingot grinding unit, the laser irradiation unit, and the wafer peeling unit; At least a quality inspection unit is disposed adjacent to the belt conveyor unit; The quality inspection unit is an ingot quality inspection unit that inspects the top surface of the ingot ground by the ingot grinding unit for defects that may prevent the laser beam from being incident on the top surface of the ingot.

2. The quality inspection unit includes a wafer quality inspection unit that inspects the quality of a wafer peeled off from an ingot, 2. The wafer generation apparatus as described in claim 1, wherein the wafer quality inspection unit includes an illuminator, an imaging means for receiving light reflected from the top surface of the wafer by the light illuminator, and a defect detection means for processing the image captured by the imaging means and detecting defects.

3. 2. The wafer generating apparatus according to claim 1, wherein the ingot quality inspection unit includes an illuminator, an imaging means for receiving light reflected from the illuminator on the top surface of the ingot, and a defect detection means for processing the image captured by the imaging means and detecting defects.

4. A wafer producing apparatus for producing wafers from an ingot, comprising: an ingot grinding unit including at least a first holding table for holding an ingot and a grinding means for grinding and flattening an upper surface of the ingot held on the first holding table; a laser irradiation unit including at least a second holding table for holding an ingot and a laser irradiation means for positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of a wafer to be produced from an upper surface of the ingot held on the second holding table, and irradiating the ingot with the laser beam to form a peeling layer; a wafer separation unit including at least a third holding table for holding an ingot and a wafer separation means for holding an upper surface of the ingot held on the third holding table and separating the wafer from the separation layer; a tray having an ingot support portion for supporting an ingot and a wafer support portion for supporting a peeled wafer; a belt conveyor unit for transporting the ingots supported on the tray between the ingot grinding unit, the laser irradiation unit, and the wafer peeling unit; At least a quality inspection unit is disposed adjacent to the belt conveyor unit; The quality inspection unit includes a wafer quality inspection unit that inspects the quality of a wafer peeled off from an ingot, The wafer quality inspection unit is a wafer generation apparatus that includes an illuminator, an imaging means for receiving light reflected from the illuminator on the top surface of the wafer, a defect detection means for processing the image captured by the imaging means and detecting defects, and a wafer conveyor belt for moving the wafer parallel to the top surface of the wafer when the wafer is imaged by the imaging means.

Images