Wafer manufacturing method and separation apparatus

Abstract

The invention provides a wafer manufacturing method and a separation device, which can reduce the possibility that at least one of a wafer and an ingot is damaged when the wafer and the ingot are pulled apart after the wafer is manufactured by applying ultrasonic waves to the ingot through a liquid layer so that the ingot is separated at a plurality of separation layers. An ultrasonic wave is applied to an ingot via a liquid layer so that the ingot is separated at a plurality of separation layers to manufacture a wafer, and then the wafer and the ingot are pulled apart by relatively moving the wafer and the ingot in a predetermined direction, i.e., a direction in which each of the plurality of separation layers extends.

Description

Technical Field

[0001] The present invention relates to a wafer manufacturing method and a separation device for manufacturing wafers from an ingot. Background Art

[0002] Semiconductor device chips are generally manufactured using wafers made of single crystals such as silicon (Si), silicon carbide (SiC), gallium nitride (GaN), lithium tantalate (LiTaO3: LT), or lithium niobate (LiNbO3: LN). The wafers are manufactured, for example, by separating an ingot using a laser beam having a wavelength that is transmitted through the raw material of the ingot (for example, see Patent Document 1).

[0003] Specifically, in this method, first, the ingot and the focal point are relatively moved in a predetermined direction, and the ingot and the position where the focal point is formed are relatively moved in a direction perpendicular to the predetermined direction, in a state where the focal point where the laser beam is focused is positioned inside the ingot. Thus, a plurality of separation layers are formed inside the ingot, each of which is along a predetermined direction and includes a modified portion and a crack extending from the modified portion.

[0004] Then, in this method, an external force is applied to the ingot in such a manner as to further extend the crack. As a result, the ingot is separated at a plurality of separation layers to produce a wafer. In addition, as a method of applying an external force to the ingot in this way, the following method has been proposed: after applying ultrasonic waves to the ingot via a layer of liquid in such a manner as to produce a wafer, the wafer and the ingot are pulled apart in a direction perpendicular to the interface between the two (for example, see Patent Document 2).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-111143

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-102513

[0007] When ultrasonic waves are applied to an ingot having a plurality of separation layers formed therein through a layer of liquid, the liquid penetrates into each of the plurality of separation layers. Therefore, when the ingot is separated at the plurality of separation layers to produce wafers, a layer of liquid remains between the wafer and the ingot.

[0008] In this case, when the wafer and the ingot are pulled apart in a direction perpendicular to the interface between the two, a strong resistance due to the surface tension of the liquid layer acts. Therefore, in this case, when the wafer and the ingot are pulled apart, a strong force acts on each of the wafer and the ingot, and at least one of the two may be damaged. Summary of the invention

[0009] In view of this, an object of the present invention is to provide a chip manufacturing method and separation device, which can reduce the possibility of damage to at least one of the chip or the ingot when pulling the chip and the ingot apart after applying ultrasonic waves to the ingot through a layer of liquid so that the ingot is separated at multiple separation layers to manufacture the chip.

[0010] According to one aspect of the present invention, a method for manufacturing a wafer is provided, wherein the wafer is manufactured from an ingot, wherein the wafer manufacturing method has the following steps: a separation layer forming step, in which the ingot and the focal point are relative moved in a prescribed direction and the ingot and the position where the focal point is formed are relative moved in a direction perpendicular to the prescribed direction in a state where a focal point focused by a laser beam having a wavelength that passes through a raw material of the ingot is positioned inside the ingot, thereby forming a plurality of separation layers inside the ingot, the plurality of separation layers are respectively along the prescribed direction and respectively include a modified portion and a crack extending from the modified portion; an ultrasonic imparting step, in which, after the separation layer forming step, ultrasonic waves are imparted to the ingot via a layer of liquid so that the ingot is separated at the plurality of separation layers to manufacture the wafer; and a pulling step, in which, after the ultrasonic imparting step, the wafer and the ingot are relatively moved in a manner along the prescribed direction, thereby pulling the wafer and the ingot apart.

[0011] According to another aspect of the present invention, a method for manufacturing a chip is provided, wherein the chip is manufactured from an ingot having a plurality of separation layers formed therein, the plurality of separation layers being respectively along prescribed directions and respectively including a modified portion and cracks extending from the modified portion, wherein the method for manufacturing the chip comprises the following steps: an ultrasonic imparting step, wherein ultrasonic waves are imparted to the ingot via a layer of liquid so as to separate the ingot at the plurality of separation layers to manufacture the chip; and a pulling step, wherein after the ultrasonic imparting step, the chip and the ingot are relatively moved in a manner along the prescribed direction, thereby pulling the chip and the ingot apart.

[0012] Furthermore, in the wafer manufacturing method of the present invention, it is preferred that the plurality of separation layers are formed so that the modified portions included in each separation layer are located on the same virtual plane, and the cracks extend so as to be inclined with respect to the virtual plane.

[0013] According to another aspect of the present invention, there is provided a separation device for manufacturing a wafer from an ingot having a plurality of separation layers formed therein, the plurality of separation layers being respectively along prescribed directions and respectively including a modified portion and a crack extending from the modified portion, wherein the separation device comprises: a first holding unit for holding the ingot; a second holding unit for holding the wafer; an ultrasonic imparting unit for imparting ultrasonic waves to the ingot held by the first holding unit via a layer of liquid; a moving mechanism for moving the first holding unit and the second holding unit relative to each other along the prescribed direction; and a controller for The controller controls the unit, the ultrasonic imparting unit and the moving mechanism. The controller controls the ultrasonic imparting unit in a manner of imparting ultrasonic waves to the ingot through the layer of the liquid while controlling the first holding unit in a manner of holding the ingot so as to separate the ingot at the plurality of separation layers to manufacture the chip. Then, the controller controls the moving mechanism in a manner of moving the first holding unit and the second holding unit relative to each other along the specified direction while controlling the first holding unit in a manner of holding the ingot and the second holding unit in a manner of holding the chip so as to pull the chip away from the ingot.

[0014] Furthermore, the separation device of the present invention preferably further includes a determination unit for determining the predetermined direction.

[0015] In the present invention, after applying ultrasonic waves to an ingot through a liquid layer so as to separate the ingot at a plurality of separation layers to produce a wafer, the wafer and the ingot are relatively moved in a predetermined direction, i.e., a direction in which the plurality of separation layers extend, to thereby separate the wafer and the ingot.

[0016] In this case, the resistance caused by the surface tension of the liquid layer becomes weaker than when the wafer and the ingot are pulled apart in a direction perpendicular to the interface between the two. Therefore, in the present invention, the possibility of at least one of the wafer or the ingot being damaged during the pulling apart can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 (A) is a perspective view schematically showing an example of an ingot, Figure 1 (B) is a schematic diagram showing Figure 1 (A) is a side view of the ingot shown.

[0018] Figure 2 This is a flowchart schematically showing an example of a wafer manufacturing method for manufacturing a wafer from an ingot.

[0019] Figure 3 It is a perspective view schematically showing the state of the separation layer forming step.

[0020] Figure 4 This is a flowchart schematically showing the operation of the laser processing device when a plurality of separation layers are formed inside an ingot.

[0021] Figure 5 is a partially enlarged cross-sectional view schematically showing an ingot after the separation layer forming step.

[0022] Figure 6 It is a perspective view schematically showing an example of a separation device capable of performing an ultrasonic applying step and a pulling step.

[0023] Figure 7 It is a side view schematically showing the state of the ultrasonic applying step.

[0024] Figure 8 It is a partially enlarged cross-sectional view schematically showing an ingot after the ultrasonic wave applying step and a wafer manufactured from the ingot.

[0025] Fig. 9 (A) and Fig. 9 (B) are side views schematically showing the state of the pulling apart step.

[0026] Description of symbols

[0027] 2: laser processing device; 4: holding unit (4a: chuck table); 6: laser beam irradiation unit; 8: head; 10: housing; 11: ingot (11a: front, 11b: back); (11c: c-axis, 11d: vertical line, 11e: c-plane); 12: imaging unit; 13: primary orientation plane; 14: separation device; 15: secondary orientation plane; 16: first holding unit (16a: chuck table); 17: reforming unit; 18: V-axis direction moving mechanism; 1 9: crack; 20: frame (20a: opening); 21: separation layer; 22: motor; 23: wafer; 24: motor; 26: first movable plate; 28: second movable plate; 30: ultrasonic imparting unit; 32: vibration component; 34: connection part; 36: water supply port; 38: liquid nozzle; 40: shooting unit (determination unit); 42: second holding unit; 44: suction plate; 46: connection part; 48: controller (48a: processor, 48b: memory). DETAILED DESCRIPTION

[0028] Embodiments of the present invention will be described with reference to the drawings. Figure 1 (A) is a perspective view schematically showing an example of an ingot, Figure 1 (B) is a schematic diagram showing Figure 1 (A) is a side view of the ingot shown. Figure 1 (A) and Figure 1Ingot 11 shown in (B) is made of, for example, a single crystal of SiC, and has a cylindrical shape including a front surface 11 a and a back surface 11 b that are substantially parallel to each other.

[0029] The ingot 11 is produced by epitaxial growth. In order to reduce lattice defects formed inside, the ingot 11 is produced in such a way that the c-axis 11c of SiC is slightly inclined relative to the perpendicular line 11d of the front surface 11a and the back surface 11b. For example, the angle (deviation angle) α formed by the c-axis 11c and the perpendicular line 11d is 1° to 6° (typically 4°).

[0030] In addition, two flat portions, namely, a primary orientation plane 13 and a secondary orientation plane 15, for indicating the crystal orientation of SiC are formed on the side surface of the ingot 11. The primary orientation plane 13 is longer than the secondary orientation plane 15. The secondary orientation plane 15 is formed parallel to the intersection line where a plane parallel to the c-plane of SiC intersects the front surface 11a or the back surface 11b.

[0031] In addition, the ingot 11 may use a single crystal of a material other than SiC (e.g., Si, GaN, LT, or LN, etc.) as a raw material. In addition, one or both of the primary orientation plane 13 and the secondary orientation plane 15 may not be formed on the side surface of the ingot 11, and a cutout (notch) for indicating the crystal orientation of the raw material constituting the ingot 11 may be formed instead.

[0032] Figure 2 1 is a flowchart schematically showing an example of a method for manufacturing a wafer from an ingot 11. In this method, first, a plurality of separation layers are formed inside the ingot 11 (separation layer forming step S1), each of which is along a predetermined direction and includes a modified portion and cracks extending from the modified portion. The predetermined direction is, for example, a direction parallel to the above-mentioned intersection line, that is, a direction parallel to the secondary orientation plane 15.

[0033] Figure 3 : is a perspective view schematically showing the separation layer forming step S1. Figure 3 The X-axis direction and the Y-axis direction shown are directions perpendicular to each other on the horizontal plane, and the Z-axis direction is a direction perpendicular to the X-axis direction and the Y-axis direction (vertical direction). Figure 3 The laser processing device 2 shown is implemented.

[0034] The laser processing apparatus 2 includes a holding unit 4 for holding the ingot 11. The holding unit 4 includes a chuck table 4a having a circular holding surface substantially parallel to a horizontal plane, and a suction mechanism (not shown) communicating with the chuck table 4a.

[0035] In addition, the suction mechanism includes, for example, an air extractor, etc. When the suction mechanism is operated, suction acts on the space near the holding surface of the chuck table 4a. Therefore, when the suction mechanism is operated with the ingot 11 placed on the holding surface of the chuck table 4a, the ingot 11 is held on the holding surface.

[0036] In addition, the chuck table 4a is connected to a rotating mechanism (not shown). The rotating mechanism includes, for example, a pulley and a motor. When the rotating mechanism is operated, the chuck table 4a rotates with a straight line in the Z-axis direction passing through the center of the holding surface as the rotation axis. For example, the rotating mechanism rotates the chuck table 4a in such a manner that the secondary orientation plane 15 of the ingot 11 held on the holding surface of the chuck table 4a is parallel to the X-axis direction.

[0037] A head 8 of the laser beam irradiation unit 6 is provided above the chuck table 4a. The head 8 is provided at the front end of a cylindrical housing 10 extending in the Y-axis direction. In addition, the head 8 accommodates an optical system such as a condenser lens (e.g., a condenser lens having a numerical aperture (NA) of 0.65) and a reflector, and the housing 10 accommodates an optical system such as a reflector and / or a lens.

[0038] The base end of the housing 10 is connected to a moving mechanism. The moving mechanism includes, for example, a ball screw and a motor. When the moving mechanism is operated, the head 8 and the housing 10 move along the X-axis direction, the Y-axis direction, and / or the Z-axis direction. In addition, the laser beam irradiation unit 6 includes, for example, a laser oscillator (not shown) containing a laser medium such as Nd:YAG.

[0039] The laser oscillator generates a pulsed laser beam (e.g., a pulsed laser beam having a frequency of 60 kHz and a pulse width of 4 ns) of a wavelength (e.g., 1064 nm) that transmits the raw material of the ingot 11. After the output (power) of the laser beam is adjusted by an attenuator (e.g., adjusted so that the average output becomes 1.5 W), the laser beam is emitted from the head 8 toward the bottom through the optical system housed in the housing 10 and the head 8.

[0040] Furthermore, a photographing unit 12 capable of photographing the area directly below is provided on the side of the housing 10. The photographing unit 12 includes, for example, a light source such as an LED (Light Emission Diode), an objective lens, and photographing elements such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

[0041] When the separation layer forming step S1 is performed using the laser processing device 2, first, the ingot 11 is placed on the holding surface of the chuck table 4a in such a manner that the front surface 11a faces upward. Then, the suction mechanism is operated in such a manner that the ingot 11 is held on the holding surface. Then, based on the image of the front surface 11a of the ingot 11 formed by the imaging unit 12, the rotation mechanism rotates the chuck table 4a so that the prescribed direction (i.e., the direction parallel to the secondary orientation plane 15) is parallel to the X-axis direction.

[0042] Next, a plurality of separation layers are formed inside the ingot 11 . Figure 4 1 is a flowchart schematically showing the operation of the laser processing device 2 when a plurality of separation layers are formed inside the ingot 11. Specifically, first, the moving mechanism moves the head 8 and the housing 10 along the X-axis direction and / or the Y-axis direction so that the region slightly inside the secondary orientation plane 15 in the ingot 11 is positioned in the X-axis direction when viewed from the head 8 in a top view.

[0043] Next, the moving mechanism moves the head 8 and the housing 10 in the Z-axis direction so that the focal point (for example, a focal point with a diameter of 3.0 μm) where the laser beam emitted from the head 8 converges is positioned at a predetermined depth (for example, a depth of 300 μm from the front surface 11a) from the front surface 11a of the ingot 11. Next, while emitting the laser beam from the head 8, the head 8 and the housing 10 are moved in the X-axis direction at a predetermined speed (for example, 200 mm / s) so that the focal point where the laser beam converges passes from one end to the other end of the ingot 11 in the X-axis direction.

[0044] That is, in a state where the focal point of the laser beam is positioned inside the ingot 11, the ingot 11 and the focal point are relatively moved along the X-axis direction (laser beam irradiation step S11). As a result, a modified portion 17 in which the crystal structure of the raw material of the ingot 11 (here, SiC) is disturbed is formed inside the ingot 11 with the focal point of the laser beam as the center.

[0045] Then, when the laser beam irradiation to the entire area of ​​the ingot 11 is not completed (step S12: No), the ingot 11 and the position where the focal point is formed are relatively moved along the Y-axis direction (indexing feeding step S13). Specifically, the moving mechanism moves the head 8 and the housing 10 along the Y-axis direction by a predetermined indexing amount (for example, 250 μm to 400 μm) so that the head 8 is positioned in the X-axis direction when viewed from a region slightly away from the secondary orientation plane 15 than the region already irradiated with the laser beam.

[0046] Next, the laser beam irradiation to the ingot 11 is performed again as described above (i.e., the laser beam irradiation step S11). Furthermore, the indexing feeding step S13 and the laser beam irradiation step S11 are repeated alternately until the laser beam is irradiated to the area farthest from the secondary orientation plane 15 in the ingot 11 and the laser beam irradiation to the entire area of ​​the ingot 11 is completed. Thus, the separation layer forming step S1 is completed.

[0047] Figure 5 1 is a partially enlarged cross-sectional view schematically showing the ingot 11 after the separation layer forming step S1. In the separation layer forming step S1, a plurality of modified portions 17 are formed, each extending along a predetermined direction (here, the X-axis direction) and each having its center located at a predetermined depth from the front surface 11a of the ingot 11.

[0048] In other words, in the separation layer forming step S1, a plurality of modified portions 17 are formed at equal intervals in a direction perpendicular to a predetermined direction (here, the Y-axis direction) and on an imaginary plane substantially parallel to the front surface 11a of the ingot 11. When the modified portion 17 is formed inside the ingot 11, the volume of the ingot 11 expands and internal stress is generated in the ingot 11.

[0049] The cracks 19 extend from the plurality of modified portions 17 to relieve the internal stress. The cracks 19 extend along the c-plane 11e inclined with respect to the front surface 11a of the ingot 11. Therefore, the cracks 19 extend with respect to the virtual plane on which the plurality of modified portions 17 are positioned.

[0050] As a result, in the separation layer forming step S1 , a plurality of separation layers 21 are formed inside the ingot 11 , each of which is along a predetermined direction and includes the modified portion 17 and the cracks 19 that have developed from the modified portion 17 .

[0051] After the separation layer forming step S1, after applying ultrasonic waves to the ingot 11 through the liquid layer so that the ingot 11 is separated at multiple separation layers 21 to manufacture a chip (ultrasonic wave applying step S2), the chip and the ingot 11 are moved relative to each other in a prescribed direction to pull the chip and the ingot 11 apart (pulling step S3).

[0052] Figure 6 Schematically shows an example of a separation device capable of performing the ultrasonic imparting step S2 and the pulling step S3. Figure 6 The U-axis direction and the V-axis direction shown are directions perpendicular to each other on the horizontal plane, and the W-axis direction is a direction perpendicular to the U-axis direction and the V-axis direction (vertical direction). Figure 6 In the figure, a part of the components of the separation device is represented by a frame.

[0053] Figure 6 The illustrated separation device 14 has a first holding unit 16 for holding the ingot 11. The first holding unit 16 includes a chuck table 16a having a circular holding surface substantially parallel to a horizontal plane and a suction mechanism (not shown) communicating with the chuck table 16a.

[0054] In addition, the suction mechanism includes, for example, an air extractor, etc. When the suction mechanism is operated, suction acts on the space near the holding surface of the chuck table 16a. Therefore, when the suction mechanism is operated in a state where the ingot 11 is placed on the holding surface of the chuck table 16a, the ingot 11 is held on the holding surface.

[0055] In addition, the chuck table 16a is connected to a rotating mechanism (not shown). The rotating mechanism includes, for example, a pulley and a motor. When the rotating mechanism is operated, the chuck table 16a rotates with a straight line in the W-axis direction passing through the center of the holding surface as the rotation axis. For example, the rotating mechanism rotates the chuck table 16a in such a way that the secondary orientation plane 15 of the ingot 11 held on the holding surface of the chuck table 16a is parallel to the V-axis direction.

[0056] In addition, the chuck table 16a is connected to a W-axis direction moving mechanism. The W-axis direction moving mechanism includes, for example, a ball screw and a motor. When the W-axis direction moving mechanism is operated, the chuck table 16a moves along the W-axis direction, that is, the chuck table 16a is raised or lowered. For example, the W-axis direction moving mechanism raises the chuck table 16a in such a manner that the ingot 11 held on the holding surface of the chuck table 16a approaches the ultrasonic imparting unit 30 or the second holding unit 42 described later.

[0057] A V-axis moving mechanism 18 is provided obliquely above the chuck table 16a. The V-axis moving mechanism 18 has a quadrangular column-shaped frame 20, which extends along the V-axis direction and has an opening 20a formed on the side surface of the chuck table 16a. The frame 20 contains a first ball screw (not shown) and a second ball screw (not shown).

[0058] The base end of the screw shaft of the first ball screw is connected to the motor 22 through a through hole formed at one end (rear end) of the frame 20. Similarly, the base end of the screw shaft of the second ball screw is connected to the motor 24 through a through hole formed at the other end (front end) of the frame 20. In addition, the base end of the first movable plate 26 and the base end of the second movable plate 28 are inserted into the opening 20a of the frame 20.

[0059] Furthermore, the base end of the first movable plate 26 is fixed to the nut of the first ball screw. Similarly, the base end of the second movable plate 28 is fixed to the nut of the second ball screw. Therefore, when at least one of the motor 22 or the motor 24 is operated, at least one of the first movable plate 26 or the second movable plate 28 moves along the V-axis direction within a range where they do not contact each other.

[0060] At the front end of the first movable plate 26, there are provided: an ultrasonic imparting unit 30 for imparting ultrasonic waves to the ingot 11 held by the first holding unit 16 via a layer of liquid; and a photographing unit (determination unit) 40 for forming an image for determining the directions (prescribed directions) in which the multiple separation layers 21 formed in the ingot 11 extend respectively.

[0061] The ultrasonic applying unit 30 has a cylindrical vibrating member 32 having a lower surface that can face the upper surface (for example, the front surface 11a) of the ingot 11 held by the first holding unit 16. The vibrating member 32 has an ultrasonic vibrator built therein, and the vibration of the ultrasonic vibrator causes the vibrating member 32 to vibrate as a whole.

[0062] In addition, the top end (lower end) of the connection portion 34 is fixed to the central area of ​​the upper surface of the vibrating member 32. And, the connection portion 34 is fixed to the lower surface side of the front end portion of the first movable plate 26. In addition, at the corner of the upper surface of the first movable plate 26, a cylindrical water supply port 36 is provided to supply liquid (e.g., water) from a liquid supply source (not shown) via a pipe (not shown) and a valve (not shown).

[0063] The liquid supplied to the water supply port 36 is supplied to the liquid nozzle 38, which is provided at a position adjacent to the vibrating member 32 and the connecting portion 34 in the V-axis direction. The liquid is supplied to the lower surface of the vibrating member 32 through the flow path in the liquid nozzle 38 from the opening provided on the lower surface.

[0064] The imaging unit 40 includes, for example, a light source such as an LED that irradiates light having a wavelength that is transmitted through the ingot 11 , an objective lens, and an imaging element such as a CCD image sensor or a CMOS image sensor, and can image an area directly below.

[0065] Further, a second holding unit 42 for holding wafers produced by separating the ingot 11 at the plurality of separation layers 21 is provided at the front end of the second moving plate 28. The second holding unit 42 has a suction plate 44 having a plurality of suction ports on its lower surface.

[0066] The plurality of suction ports are connected to a suction mechanism (not shown) such as an air extractor via a flow path (not shown) provided inside the suction plate 44, a pipe (not shown) connected to the flow path, a valve (not shown), etc. In addition, the front end (lower end) of the connection portion 46 is fixed to the central area of ​​the upper surface of the suction plate 44. The connection portion 46 is fixed to the lower surface side of the front end portion of the second movable plate 28.

[0067] The separation device 14 has a controller 48 for controlling various components (for example, the first holding unit 16, the V-axis direction moving mechanism 18, the ultrasonic applying unit 30, the imaging unit 40, and the second holding unit 42). The controller 48 has a processor 48a and a memory 48b.

[0068] The processor 48a is composed of, for example, a CPU (Central Processing Unit), etc. In addition, the memory 48b is composed of, for example, a volatile memory such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory), and a non-volatile memory such as an SSD (Solid State Drive) (NAND flash memory) or an HDD (Hard Disk Drive) (magnetic storage device).

[0069] The memory 48b stores data and programs used by the processor 48a. The processor 48a controls each component of the separation device 14 so as to read and execute the program stored in the memory 48b.

[0070] When the ingot 11 having a plurality of separation layers 21 is carried into the separation device 14, the ingot 11 is first placed on the holding surface of the chuck table 16a with the front surface 11a facing upward. Then, the controller 48 controls the first holding unit 16 (specifically, the suction mechanism connected to the chuck table 16a) in such a manner that the ingot 11 is held.

[0071] Next, the controller 48 controls the V-axis direction moving mechanism 18 (specifically, the motor 22) so as to position the vibration member 32 just above the ingot 11. Next, the controller 48 controls the W-axis direction moving mechanism connected to the chuck table 16a so as to raise the chuck table 16a until the lower surface of the vibration member 32 approaches the front surface 11a of the ingot 11.

[0072] Next, the controller 48 controls the ultrasonic applying unit 30 to apply ultrasonic waves to the ingot 11 via the liquid layer so that the ingot 11 is separated at the plurality of separation layers 21 to manufacture wafers. That is, the ultrasonic applying step S2 is performed. Figure 7 It is a side view schematically showing the state of the ultrasonic applying step S2.

[0073] In the ultrasonic imparting step S2 , the controller 48 controls the ultrasonic vibrator built into the vibration component 32 so as to vibrate the entire vibration component 32 , and controls the liquid supply source so as to supply liquid L from the liquid nozzle 38 to the lower surface of the vibration component 32 .

[0074] At this time, the controller 48 may control the rotating mechanism connected to the chuck table 16a so as to rotate the chuck table 16a while vibrating the vibrating member 32 and supplying the liquid L to the lower surface of the vibrating member 32. Thus, ultrasonic waves are applied to the ingot 11 using the liquid L as a medium. As described above, the ultrasonic applying step S2 is completed.

[0075] Figure 8 1 is a partially enlarged cross-sectional view schematically showing the ingot 11 after the ultrasonic applying step S2 and the wafer manufactured from the ingot 11. In the ultrasonic applying step S2, the cracks 19 included in each of the plurality of separation layers 21 extend. As a result, the number of cracks exposed on the side surface of the ingot 11 increases, and the cracks 19 included in a pair of adjacent separation layers 21 are connected.

[0076] At this time, liquid L penetrates into the inside of ingot 11 through cracks 19 exposed on the side surface of ingot 11. In addition, ingot 11 is separated at a plurality of separation layers 21 to produce wafers 23. Therefore, a layer of liquid L remains at the interface between ingot 11 and wafer 23.

[0077] In addition, the cracks 19 included in each of the plurality of separation layers 21 extend along the c-plane 11e inclined with respect to the front surface 11a of the ingot 11. Therefore, the newly exposed surfaces of the ingot 11 and the wafer 23 each have a shape that is undulated in a direction perpendicular to the direction (prescribed direction) in which the plurality of separation layers 21 formed on the ingot 11 extend. In other words, these surfaces have a shape in which the maximum height fluctuation Wz in the prescribed direction becomes small, but the maximum height fluctuation Wz in the direction perpendicular to the prescribed direction is large.

[0078] Next, the controller 48 controls the ultrasonic applying unit 30 in such a manner as to stop applying ultrasonic waves to the ingot 11 via the layer of liquid L. Specifically, the controller 48 controls the ultrasonic vibrator, the liquid supply source, and the W-axis direction moving mechanism connected to the chuck table 16a in such a manner as to stop the vibration of the vibration member 32 and the supply of the liquid L to the lower surface of the vibration member 32 and to lower the chuck table 16a.

[0079] Next, the controller 48 controls the V-axis direction moving mechanism 18 (specifically, the motor 22) so that the imaging unit 40 is positioned just above the ingot 11. Next, the controller 48 controls the imaging unit 40 so that an image for specifying a predetermined direction is formed. For example, the controller 48 controls the imaging unit 40 so that an image focusing on the interface between the ingot 11 and the wafer 23 is formed.

[0080] In this case, by referring to the image, the undulations of the newly exposed surfaces of the ingot 11 and the wafer 23 can be grasped, and thus the predetermined direction can be determined. Next, the controller 48 controls the rotation mechanism connected to the chuck table 16a so that the predetermined direction determined by referring to the image is parallel to the V-axis direction.

[0081] Next, the controller 48 controls the V-axis direction moving mechanism 18 (specifically, the motor 22 and the motor 24) so ​​that the imaging unit 40 is separated from the ingot 11 in a plan view and the suction plate 44 is positioned just above the ingot 11. Next, the controller 48 controls the W-axis direction moving mechanism connected to the chuck table 16a so that the chuck table 16a is raised until the lower surface of the suction plate 44 contacts the wafer 23.

[0082] Next, the controller 48 controls the second holding unit 42 and the V-axis direction moving mechanism 18 (specifically, the motor 24 ) so that the wafer 23 and the ingot 11 are relatively moved in the V-axis direction which is a predetermined direction. That is, the separation step S3 is performed. Fig. 9 (A) and Fig. 9 (B) are side views schematically showing the state of pulling open step S3.

[0083] In the pulling step S3, first, the controller controls the second holding unit 42 (specifically, a suction mechanism connected to a plurality of suction ports provided on the lower surface of the suction plate 44) so ​​that the wafer 23 is held by the second holding unit 42 (see Fig. 9 Next, the controller 48 controls the V-axis direction moving mechanism 18 (specifically, the motor 24) so ​​that the wafer 23 is pulled away from the ingot 11 along the V-axis direction while the wafer 23 is held by the second holding unit 42 (see Fig. 9 (B)).

[0084] exist Figure 2 In the chip manufacturing method shown, after applying ultrasonic waves to the ingot 11 through a layer of liquid L so that the ingot 11 is separated at multiple separation layers 21 to manufacture the chip 23, the chip 23 and the ingot 11 are moved relative to each other in a prescribed direction, i.e., the direction in which the multiple separation layers 21 extend respectively, thereby pulling the chip 23 and the ingot 11 apart.

[0085] In this case, the resistance caused by the surface tension of the layer of liquid L becomes weaker than when the wafer 23 and the ingot 11 are pulled apart in a direction perpendicular to the interface between the two. Therefore, in this method, the possibility of at least one of the wafer 23 or the ingot 11 being damaged during the pulling apart can be reduced.

[0086] In addition, the above content is one embodiment of the present invention, and the present invention is not limited to the above content. For example, the method for manufacturing a wafer of the present invention may also be from Figure 2 The wafer manufacturing method shown is a wafer manufacturing method that omits the separation layer forming step S1. That is, the wafer manufacturing method of the present invention may also be a wafer manufacturing method that manufactures the wafer 23 from the ingot 11 having a plurality of separation layers 21 formed therein.

[0087] In addition, the separation device of the present invention may be provided with a V-axis direction moving mechanism for moving the first holding unit 16 along the V-axis direction, instead of the V-axis direction moving mechanism 18 for moving the ultrasonic applying unit 30 and the second holding unit 42 along the V-axis direction, or in addition to the V-axis direction moving mechanism 18. That is, in the present invention, as long as the wafer 23 and the ingot 11 can be relatively moved along the above-mentioned predetermined direction, the structure for realizing the movement is not limited.

[0088] In addition, the separation device of the present invention may not include the imaging unit 40. In this case, the predetermined direction is not determined by referring to the image formed by imaging by the imaging unit 40, but is determined by visually observing the secondary orientation plane 15, for example.

[0089] In addition, the structure and method etc. which concern on the said embodiment can be implemented with appropriate modification unless it deviates from the scope of the objective of this invention.

Claims

1. A method for manufacturing a wafer from an ingot, wherein: The method for manufacturing the wafer comprises the following steps: a separation layer forming step of alternately repeating relative movement of the ingot and the light-converging point along a predetermined direction and relative movement of the ingot and the position where the light-converging point is formed along a direction perpendicular to the predetermined direction in a state where a light-converging point focused by a laser beam having a wavelength transmitted through a raw material of the ingot is positioned inside the ingot, thereby forming a plurality of separation layers inside the ingot, the plurality of separation layers respectively being along the predetermined direction and respectively including a modified portion and a crack extending from the modified portion; an ultrasonic applying step of applying ultrasonic waves to the ingot via the liquid layer after the separation layer forming step so as to separate the ingot at the plurality of separation layers to manufacture the wafer; as well as The separating step comprises, after the ultrasonic applying step, moving the wafer and the ingot relatively to each other in the predetermined direction, thereby separating the wafer and the ingot.

2. A method for manufacturing a wafer, comprising manufacturing a wafer from an ingot having a plurality of separation layers formed therein, the plurality of separation layers being respectively along a predetermined direction and respectively including a modified portion and a crack extending from the modified portion, wherein: The method for manufacturing the wafer comprises the following steps: an ultrasonic applying step of applying ultrasonic waves to the ingot through the liquid layer so as to separate the ingot at the plurality of separation layers to manufacture the wafer; and The separating step comprises, after the ultrasonic applying step, moving the wafer and the ingot relatively to each other in the predetermined direction, thereby separating the wafer and the ingot.

3. The method for manufacturing a wafer according to claim 1 or 2, wherein: The plurality of separation layers are formed in such a manner that the modified portions contained in each separation layer are located on the same imaginary plane, The crack extends in a manner inclined with respect to the imaginary plane.

4. A separation device for manufacturing a wafer from an ingot having a plurality of separation layers formed therein, the plurality of separation layers being respectively along a predetermined direction and respectively including a modified portion and cracks extending from the modified portion, wherein: The separation device has: a first holding unit for holding the ingot; a second holding unit for holding the wafer; an ultrasonic imparting unit for imparting ultrasonic waves to the ingot held by the first holding unit via the liquid layer; a moving mechanism for moving the first holding unit and the second holding unit relative to each other along the specified direction; and a controller for controlling the first holding unit, the second holding unit, the ultrasonic imparting unit and the moving mechanism, The controller controls the ultrasonic applying unit in a state where the first holding unit is controlled so as to hold the ingot, and controls the ultrasonic applying unit in a state where ultrasonic waves are applied to the ingot through the layer of the liquid so as to separate the ingot at the multiple separation layers to manufacture the chip. Then, the controller controls the moving mechanism in a state where the first holding unit is controlled so as to hold the ingot and the second holding unit is controlled so as to hold the chip, and controls the moving mechanism in a state where the first holding unit and the second holding unit are moved relative to each other in the specified direction so as to pull the chip away from the ingot.

5. The separation device according to claim 4, wherein: The separating device further comprises a determining unit for determining the prescribed direction.

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