TW201711221A - Lift-off method and ultrasonic-horn shaped radiator capable of peeling an epitaxy substrate from an optical device layer even in a case where an optical device wafer with a large diameter is peeled off - Google Patents

Abstract

The present invention is to peel an epitaxy substrate from an optical device layer even in a case where an optical device wafer with a large diameter is peeled off. A lift-off method for transferring the optical device layer (12) of the optical device wafer (10) to a transfer substrate (20) comprises: a transfer substrate bonding step in which the transfer substrate (20) is joined to a surface (12a) of the optical device layer via a bonding layer (21); a peeling layer formation step in which a pulse laser beam that is transmissive through an epitaxy substrate (11) and absorbable by a buffer layer (13) is emitted from an inner side (11a) of the epitaxy substrate (11) of the optical device wafer (10) with the transfer substrate (20) joined thereto, thereby forming a peeling layer (19) on an interface between the epitaxy substrate (11) and the buffer layer (13); and an optical device layer transfer step in which while an ultrasonic-horn shaped radiator (40) having a shape surrounding the outer peripheral edge (11c) of the epitaxy substrate (11) is kept in contact with the inner side (11d) of the outer peripheral edge (11c), the epitaxy substrate (11) is vibrated to be peeled off from the transfer substrate (20), and the optical device layer (12) is transferred to the transfer substrate (20).

Description

Stripping method and ultrasonic horn

The present invention relates to a peeling method for transferring a laminated optical element layer to a transfer substrate via a buffer layer on a surface of an epitaxial substrate, and an ultrasonic horn using the method.

In the manufacturing process of an optical element, an n-type semiconductor composed of GaN (gallium nitride) or the like is laminated on the surface of an epitaxial substrate such as a sapphire substrate or a tantalum carbide substrate having a substantially circular plate shape via a buffer layer. The optical element layer formed by the layer and the p-type semiconductor layer forms an optical element such as a light-emitting diode or a laser diode in a plurality of regions drawn by forming a lattice-shaped complex ruled line. Optical component wafer. Therefore, one optical element is manufactured by dividing the optical element wafer along the ruled line (for example, refer to Patent Document 1).

Further, as a technique for improving the brightness of an optical element, there is also a method of manufacturing an optical element called transfer peeling in which a spacer layer is laminated on the surface of an epitaxial substrate constituting an optical element wafer. The optical element layer is bonded to a transfer substrate such as Mo (molybdenum), Cu (copper), or Si (yttrium) by a bonding layer such as AuSn (gold tin), and is formed in the epitaxial substrate. On the surface side, laser light having a wavelength that is transparent to the epitaxial substrate and having absorption to the buffer layer is irradiated, and the epitaxial substrate is peeled off from the optical element layer by breaking the buffer layer, and the optical element layer is transferred and transferred to the transfer substrate. (For example, refer to Patent Document 2). In addition, since the buffer layer is irradiated with laser light, the buffer layer may not be sufficiently damaged. In order to completely peel the epitaxial substrate from the optical element, the germanium substrate is irradiated with ultrasonic waves through the pure water impregnated with the ruthenium substrate. A method of peeling off a metal film on a tantalum substrate (for example, see Patent Document 3).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] JP H10-305420 A

[Patent Document 2] JP 2004-72052 A

[Patent Document 3] JP 2011-103361 A

Here, the invention of Patent Document 3 does not disclose the contents of the transfer optical element layer at all, and includes a method of performing engineering in water, which has a problem of taking time. Further, in the case where the diameter of the optical element wafer exceeds 2 Å, so that it is 4 吋 and 6 吋, it is difficult to peel the epitaxial substrate from the optical element layer.

The present invention has been made in view of the above circumstances, and an object to be solved is that an epitaxial group can be used even when an optical element wafer having a large diameter is peeled off. The plate is completely peeled off from the optical element layer.

In order to solve the above problems, the present invention provides a peeling method in which an optical element layer of an optical element wafer laminated by an optical element layer is transferred to a surface of an epitaxial substrate via a buffer layer made of GaN. Disposing a substrate, wherein the stripping method comprises: transferring a substrate on a surface of the optical element layer of the optical element wafer via a bonding layer, and transferring the substrate from the optical element wafer to which the transfer substrate is bonded; On the back side of the substrate, a pulsed laser beam having a wavelength that is transparent to the epitaxial substrate and having an absorptivity to the buffer layer is irradiated, and a peeling layer forming a peeling layer is formed on the interface between the epitaxial substrate and the buffer layer; After forming the project, an ultrasonic horn that oscillates the ultrasonic wave around the outer periphery of the epitaxial substrate is used to at least contact the inside of the outer periphery and vibrate the epitaxial substrate to make the epitaxial substrate The transfer substrate is peeled off, and the optical element layer is transferred to the optical element layer transfer project of the transfer substrate.

Further, in order to solve the above-described problems, the ultrasonic horn radiating body used in the peeling method includes an arc shape formed along a periphery of the epitaxial substrate and contacting the inside of the outer peripheral edge of the epitaxial substrate. a contact surface; and an outer side surrounding surface surrounding the outer surface of the epitaxial substrate and determining the position.

In the peeling method of the present invention, in the optical element layer shifting process, an ultrasonic horn having an outer peripheral edge shape surrounding the epitaxial substrate and oscillating the ultrasonic wave is used, at least contacting the inside of the outer periphery, and borrowing By vibrating the epitaxial substrate, even if the optical element wafer has a large diameter, the epitaxial substrate can be completely removed from the optical element layer, so that the optical element layer can be more easily transferred to the transfer substrate.

Further, the ultrasonic horn of the present invention has an arcuate shape along the periphery of the epitaxial substrate, an inner contact surface contacting the outer periphery of the epitaxial substrate, and an outer side surrounding the epitaxial substrate. And determining the outer side of the position to surround the surface; by using the stripping method of the present invention, the ultrasonic wave can be sufficiently propagated from the outer periphery of the epitaxial substrate to the epitaxial substrate, thereby further improving the efficiency of vibration propagation, and the optical element layer can be more easily Move to the transfer substrate.

10‧‧‧Optical component wafer

11‧‧‧ epitaxial substrate

11a‧‧‧ Surface of the epitaxial substrate

11b‧‧‧ inside the epitaxial substrate

11c‧‧‧ outer periphery of the epitaxial substrate

11d‧‧‧The inside of the outer circumference

11e‧‧‧Outer side of the epitaxial substrate

12‧‧‧Optical element layer

12A‧‧‧n type gallium nitride semiconductor layer

12B‧‧‧p type GaN semiconductor layer

12a‧‧‧ Surface of the optical component layer

13‧‧‧buffer layer

15‧‧‧Split line

16‧‧‧Optical components

19‧‧‧ peeling layer

19a‧‧‧N ₂ gas layer

20‧‧‧Transfer substrate

20a‧‧‧Transfer the bottom surface of the substrate

20b‧‧‧Transfer the surface of the substrate

20c‧‧‧Removal of the exposed part of the substrate

21‧‧‧ joint layer

25‧‧‧Composite substrate

30‧‧‧ Laser processing equipment

31‧‧‧ cutting disk

32‧‧‧Laser light irradiation

32a‧‧‧Laser light oscillation

32b‧‧‧Mirror

32c‧‧‧ collecting lens

33‧‧‧Revolving means

40‧‧‧Supersonic horn

400‧‧‧天板

400a‧‧‧ inside contact surface

401‧‧‧ side panels

401a‧‧‧The outer side is surrounded by the surface

401b‧‧‧ lower surface of the side panel

402‧‧‧ convex

403‧‧‧Supersonic oscillator

404‧‧‧Mobile means

L1‧‧‧ length

44‧‧‧Support desk

45‧‧‧moving means

46‧‧‧Attraction mat

47‧‧‧Attraction source

Fig. 1 (A) is a perspective view of an optical element wafer. Fig. 1(B) is a partial cross-sectional view showing an optical element wafer.

2(A) is a perspective view showing a state in which a transfer substrate is bonded to a surface of an optical element layer of an optical element wafer in a transfer substrate bonding process via a bonding layer. 2(B) is a perspective view showing a state in which the transfer substrate is bonded to the surface of the optical element layer of the optical element wafer in the transfer substrate bonding process via the bonding layer. 2(C) is a partial cross-sectional view showing the optical element wafer on which the substrate is transferred and transferred via the bonding layer on the surface of the optical element layer.

Fig. 3 is a perspective view showing a state in which pulsed laser light is irradiated onto an optical element wafer in a peeling layer forming process.

Fig. 4 is a side view showing a state in which pulsed laser light is irradiated onto an optical element wafer in a peeling layer forming process.

Fig. 5 is a plan view showing a trajectory of an irradiation position of a pulsed laser beam on the inside of an epitaxial substrate of an optical element wafer in a peeling layer forming process.

Fig. 6 is a perspective view as seen from the back side of the epitaxial substrate when the peeling layer of the optical element wafer is irradiated with pulsed laser light in the peeling layer forming process.

Fig. 7 (A) is a perspective view showing an ultrasonic horn radiator used in the peeling method of the present invention. Fig. 7(B) is a perspective view showing the ultrasonic horn radiator used in the peeling method of the present invention in an upright state. Fig. 7(C) is a schematic view showing the end face of the main portion in contact with the ultrasonic horn radiator to the epitaxial substrate.

[Fig. 8] Fig. 8 is a schematic view showing a state of a partial end face in which an ultrasonic horn radiating body contacts the inside of the outer peripheral edge of the epitaxial substrate and the epitaxial substrate is vibrated in the optical element layer transfer process.

Fig. 9 is a schematic plan view showing a state in which the ultrasonic element layer is transferred to the inside of the outer peripheral edge of the epitaxial substrate and the epitaxial substrate is vibrated in the optical element layer.

Fig. 10 (A) is a perspective view showing a state in which an epitaxial substrate is suction-supported by an attraction pad in an optical element layer transfer process. Fig. 10(B) shows the epitaxial support of the attraction support by the attraction pad in the optical element layer transfer project A state in which the substrate is peeled off from the optical element layer is a schematic oblique view.

The optical element wafer 10 shown in FIG. 1(A) and FIG. 1(B) has, for example, an epitaxial substrate 11 formed of a disk-shaped sapphire substrate having a diameter of 4 Å and a thickness of 600 μm, and an epitaxial substrate 11; The optical element layer 12 is laminated on the side of the surface 11a. The optical element layer 12 is an n-type gallium nitride semiconductor layer 12A and a p-type gallium nitride semiconductor layer 12B (not shown in FIG. 1(A)) formed by epitaxial growth on the surface 11a of the epitaxial substrate 11. form. When the optical element layer 12 having a thickness of 10 μm is laminated on the epitaxial substrate 11, a buffer layer 13 having a thickness of, for example, 1 μm made of GaN is formed between the surface 11a of the epitaxial substrate 11 and the p-type gallium nitride semiconductor layer 12B. (Not shown in Figure 1 (A)). The optical element layer 12 forms an optical element 16 (not shown in Fig. 1(B)) in a plurality of regions drawn by a plurality of predetermined dividing lines 15 in a lattice shape.

Hereinafter, the operation of the peeling method of the present embodiment and the operation of the ultrasonic horn used in the optical element layer transfer process when the peeling method is performed will be described with reference to Figs. However, each of the items shown in FIGS. 2 to 10 is only one example, and is not limited to this structure.

(1) Transfer substrate bonding project

First, as shown in FIG. 2(A) to FIG. 2(C), on the surface of the optical element layer 12 of the optical element wafer 10, a bonding layer 21 is interposed (not shown). 2(A)), a transfer substrate bonding process of bonding the transfer substrate 20 is performed.

In the transfer substrate bonding process, the transfer substrate 20 formed of, for example, a copper substrate having a thickness of 1 mm is bonded to the surface 12a of the optical element layer 12 via the bonding layer 21. Further, as the transfer substrate 20, Mo, Cu, Si, or the like can be used, and the bonding layer 21 can be, for example, Au (gold), Pt (platinum), Cr (chromium), In (indium), or Pd (palladium). Etching the metal.

In the transfer substrate bonding process, the bonding metal is deposited on the surface 12a of the optical element layer 12 or the bottom surface 20a of the transfer substrate 20 to form a bonding layer 21 having a thickness of, for example, about 3 μm. Next, the bonding layer 21 is pressed face-to-face with the bottom surface 20a of the transfer substrate or the surface 12a of the optical element layer 12. Thereby, the optical element wafer 10 and the transfer substrate 20 are bonded to each other via the bonding layer 21 to form the composite substrate 25. However, the bonding layer 21 is omitted in FIGS. 4, 7(C), and 8.

(2) Formation of peeling layer

After the transfer substrate bonding process is performed, as shown in FIG. 3, from the side of the back surface 11b of the epitaxial substrate 11 of the optical element wafer 10 on which the substrate 20 is bonded, the irradiation is transparent to the epitaxial substrate 11, and the buffer is applied. The layer 13 has pulsed laser light having an absorptive wavelength, and a peeling layer forming process of forming a peeling layer on the interface between the epitaxial substrate 11 and the buffer layer 13 is performed.

In the peeling layer forming process, the cutting disk 31 including the laser processing apparatus 30 is placed on the upper surface of the supporting surface, and is placed on the cutting disk 31 so as to connect the surface 20b of the transfer substrate 20 of the composite substrate 25. Connect The suction is supported by the suction means connected to the cutting disk 31 (not shown), and the composite substrate 25 is adsorbed and supported on the cutting disk 31. Then, the laser light irradiation means 32 including a current scanner or the like is used to move the light collecting lens 32c included in the laser light irradiation means 32 and the epitaxial substrate 11 of the composite substrate 25 by a moving means (not shown). The inside 11b faces the surface, and the laser light irradiation position of the laser light irradiation means 32 is disposed at the outermost periphery of the epitaxial crystal 11. Thereafter, as shown in FIG. 4, pulsed laser light is irradiated from the inner surface 11b side of the epitaxial substrate by the laser light irradiation means 32. The laser light irradiation means 32 sets a wavelength which is transparent to the epitaxial substrate 11 and has absorption to the buffer layer 13 from the side of the laser light oscillating means 32a, and oscillates the pulsed laser light. Therefore, the pulsed laser light oscillated from the laser light oscillation means 32a is reflected by the mirror 32b and enters the collecting lens 32c. The collecting lens 32c concentrates the light to the buffer layer 13 and illuminates the collected laser light.

The mirror 32b is constituted by a motor mirror or the like, and the reflection angle can be adjusted, and the pulsed laser light collected by the collecting lens 32c is set to be scanable in any direction along the plane direction of the buffer layer 13. As shown in FIG. 5, the mirror 32b is adjusted so that the light collecting point of the pulsed laser light is scanned from the outermost periphery of the inner surface 11b of the epitaxial substrate 11 and the center of the epitaxial substrate 11 is drawn in a spiral trajectory. Thereby, the entire area corresponding to the buffer layer 13 is irradiated with the pulsed laser light, so that the GaN constituting the buffer layer 13 is decomposed into N ₂ gas and Ga. Therefore, as shown in FIG. 4, a plurality of island-shaped peeling layers 19 composed of the N ₂ gas layer 19a and the Ga layer are formed on the interface between the epitaxial substrate 11 and the buffer layer 13. Then, although the N ₂ gas layer 19a may be formed on the entire surface of the buffer layer 13, as shown in FIG. 6, the N ₂ gas layer 19a tends to be uniformly formed in a wide range of regions close to the periphery of the epitaxial substrate 11. Then, in the peeling layer forming process, when the epitaxial substrate 11 having a diameter of 4 Å is irradiated with pulsed laser light, for example, the laser light irradiation position of the laser light irradiation means 32 is set on the epitaxial substrate 11 At the outermost periphery, by rotating the cutting disk 31 by the turning means 33 shown in FIG. 4 disposed at the lower portion of the cutting disk 31, by moving the laser light irradiation means 32 toward the center of the inner surface 11b of the epitaxial substrate 11, The buffer layer 13 is subjected to comprehensive pulsed laser light irradiation.

The above-described peeling layer forming process can be carried out, for example, by the following laser processing conditions.

Light source: YAG laser

Wavelength: 257nm

Repeat frequency: 50kHz

Average output: 0.12W

Pulse amplitude: 100ps

Peak power: 5μJ-3μJ

Dot diameter: 70μm

Laser light irradiation means moving speed: 50-100mm / sec

(3) Optical component layer transfer engineering

After the peeling layer forming process is performed, as shown in FIGS. 8 to 9, an ultrasonic horn 40 having an outer peripheral edge 11c surrounding the epitaxial substrate 11 and oscillating ultrasonic waves is used, at least contacting the outer peripheral edge 11c. Inside 11d, and vibrating the epitaxial substrate 11 to move the epitaxial substrate 11 from the substrate 20 is peeled off, and the optical element layer 12 is transferred to the transfer substrate 20 to perform an optical element layer transfer process. Further, the outer peripheral edge 11c of the epitaxial substrate 11 is, for example, a portion having a certain area formed by the outer surface 11e of the epitaxial substrate 11 and the annular surface 11d occupying the outermost portion of the inner surface 11b of the epitaxial substrate 11. . That is, the inner surface of the outer peripheral edge 11c of the epitaxial substrate 11 is flush with the annular surface 11d which occupies the outermost peripheral portion of the inner surface 11b of the epitaxial substrate 11.

The ultrasonic horn 40 shown in Figs. 7(A) to 7(C) is, for example, a semi-annular slab 400, and a half ring vertically hanging from the periphery of the stencil 400 in the -Z direction. The side plate 401 and the convex portion 402 projecting from the outer side of the side plate 401 have a semicircular arc shape along the outer periphery of the epitaxial substrate 11 in the present embodiment. Therefore, the cross section of the ultrasonic horn 40 is, for example, an inverted L shape. Further, the ultrasonic horn 40 can be moved in the vertical direction (Z-axis direction) and the horizontal direction (X-axis direction and Y-axis direction) by the moving means 404. Further, the overall shape of the ultrasonic horn 40 is not limited to a semicircular arc shape, and may be an arc shape along the outer periphery of the epitaxial substrate 11.

The lower surface of the top plate 400 forms an inner contact surface 400a that is in contact with the inner surface 11d of the outer peripheral edge 11c of the epitaxial substrate 11, and is provided from the ultrasonic oscillator 403 disposed on the convex portion 402 (not shown in FIG. 7 (B). )) The oscillated ultrasonic vibration propagates from the inner contact surface 400a to the epitaxial substrate 11. The inner diameter of the semi-annular side plate 401 (the diameter of the half-ring hollow portion) is the same as or larger than the outer diameter of the epitaxial substrate 11, and the inner circumferential side surface of the side plate 401 surrounds the outer surface 11e of the epitaxial substrate 11, and is determined. The outer side of the location surrounds the face 401a. and also That is, for example, the ultrasonic horn radiator 40 determines the position of the epitaxial substrate 11 by surrounding the outer side surface 401a and contacting the outer side surface 11e of the epitaxial substrate 11. Further, the length of the outer side surrounding surface 401a in the vertical direction (Z-axis direction), that is, the length L1 from the inner contact surface 400a to the lower surface 401b of the side plate 401 (not shown in FIG. 7(A)), is epitaxial. The length of the substrate 11 is equal to or less than the thickness.

As shown in FIG. 8, in the optical element layer transfer project, first, the support table 44 including the transfer device 4 is placed on the upper surface of the support surface, and is placed on the surface 20b of the transfer substrate 20 of the composite substrate 25. The support station 44 is on. Next, suction is performed by a suction means connected to the support table 44 (not shown), and the composite substrate 25 is adsorbed and supported on the cutting disk 44. Next, as shown in FIG. 9, the two ultrasonic horns 40 are respectively moved toward the composite substrate 25 by the moving means 404 and opposed to the outer side surrounding surface 401a of each of the ultrasonic horns 40. Moving, the alignment of the epitaxial substrate 11 with the two ultrasonic horns 40 is performed. However, only one side of the ultrasonic horn 40 is illustrated in FIG. In this pair, as shown in FIG. 8, for example, the outer side surface of the ultrasonic horn 40 is surrounded by the surface 401a, and the epitaxial substrate 11 is surrounded in a state of connecting the outer side surface 11e of the epitaxial substrate 11. Therefore, in the present embodiment, for example, by using two ultrasonic horns 40 on the circumference of the epitaxial substrate 11, the ultrasonic horn 40 is surrounded by the entire epitaxial crystal as shown in FIG. The state of the outer peripheral edge 11c of the substrate 11.

Next, as shown in FIG. 8, the ultrasonic horn 40 having the ultrasonic oscillator 403 is activated as follows: from the ultrasonic oscillator 403, for example, is an ultrasonic oscillation having a frequency of 20 kHz and an amplitude of 20 μm with respect to the vertical direction (Z-axis direction) of the inner surface 11b of the epitaxial substrate 11 in the amplitude direction. The ultrasonic wave can appropriately change the frequency and the amplitude. For example, if the thickness of the optical element wafer 10 is reduced, the ultrasonic wave amplitude can be made small. Further, the two ultrasonic horns 40 are lowered in the -Z direction so that the inner contact faces 400a of the respective ultrasonic horns 40 are in contact with the inner face 11d of the outer periphery 11c of the entire epitaxial substrate 11, that is, The annular surface 11d occupying the outermost portion of the inner surface 11b of the entire epitaxial substrate 11 is contacted by the inner contact surface 400a of the two ultrasonic horns 40 to oscillate from the ultrasonic oscillator 403. The sound waves propagate toward the epitaxial substrate 11. Therefore, the epitaxial substrate 11 vibrates in the vertical direction (Z-axis direction) due to the propagation of ultrasonic waves. Here, for example, when the diameter of the transfer substrate 20 is larger than the diameter of the optical element wafer 10 and the transfer between the transfer substrate 20 and the optical element wafer 10 is shifted in the transfer substrate bonding process, There is a case where the protruding portion 20c is formed on the transfer substrate 20 as shown in FIG. Even in this case, the length L1 (see FIG. 7(C)) from the inner contact surface 400a of the ultrasonic horn 40 to the lower surface 401b of the side plate 401 is the length below the thickness of the epitaxial substrate 11, super The outer side surrounding surface 401a of the acoustic horn 40 is not connected to the transfer substrate 20. Therefore, no ultrasonic waves are propagated to the transfer substrate 20.

Here, it is presumed that the ultrasonic vibration propagates from the epitaxial substrate 11 via the N ₂ gas layer 19a of the peeling layer 19. That is, by the shaking of the N ₂ gas layer 19a in the Z-axis direction, the bonding between the epitaxial substrate 11 and the optical element layer 12 joined by the buffer layer 13 is gradually broken. Therefore, the peripheral portion of the surface 11a of the epitaxial substrate 11 which the ultrasonic horn 40 is in contact with, since the uniform and wide-range N ₂ gas layer 19a is formed in the peeling layer 19, the polar portion is close to the N ₂ gas layer 19a. The position immediately above and the like can be sufficiently oscillated, and the N ₂ gas layer 19a breaks the bond between the epitaxial substrate 11 and the optical element layer 12 joined by the buffer layer 13 toward the center of the peeling layer 19, and simultaneously The peripheral side begins to diffuse, which can increase the efficiency of vibration propagation.

Further, in order to provide ultrasonic vibration to the epitaxial substrate 11, two ultrasonic horns 40 may be used together on the circumference of the epitaxial substrate 11, and only one ultrasonic horn 40 may be used along the ray. The outer peripheral edge 11c of the crystal substrate 11 is moved in the circumferential direction.

Further, for example, when the ultrasonic horn 40 has an arc shape shorter than the semicircle, two or more ultrasonic horns 40 may be used together on the circumference of the epitaxial substrate 11 to provide Ultrasonic vibration.

After the ultrasonic vibration is supplied using the ultrasonic horn 40, the moving means 45 as shown in FIG. 10(A), and the vertical direction (Z-axis direction) and the horizontal direction (X-axis direction and Y-axis direction) Moving the possible attraction pads 46, the epitaxial substrate 11 can be attracted and supported. The suction pad 46 is connected to the suction source 47, and is attracted to the suction surface (lower surface) of the suction pad 46 composed of a porous member or the like by the suction force of the suction source 47, and the suction pad 46 sucks and supports the epitaxial substrate 11 on the suction surface.

First, the attraction pad 46 is moved by the moving means 45 to The epitaxial substrate 11 is then lowered in the -Z direction by the suction pad 46, and the suction surface (lower surface) of the suction pad 46 is brought into contact with the inner surface 11b of the epitaxial substrate 11 of the composite substrate 25. Therefore, the suction source 47 is actuated, and the inner surface 11b of the epitaxial substrate is attracted by the suction surface of the suction pad 46. Therefore, as shown, the attraction pad 46 is raised by the moving means 45 from the +Z direction away from the support table 44. Thereby, the epitaxial substrate 11 is peeled off from the optical element layer 12, and the transfer of the optical element layer 12 to the transfer substrate 20 is completed.

Therefore, in the peeling method of the present embodiment, in the optical element layer transfer process, the ultrasonic horn radiator 40 contacts at least the inner surface 11d of the outer peripheral edge 11c of the epitaxial substrate 11 and vibrates the epitaxial substrate 11, as described above. The ultrasonic vibration is propagated with high efficiency. Thereby, the bond between the epitaxial substrate 11 and the optical element layer 12 joined by the buffer layer 13 can be sufficiently broken. Therefore, even if the object to be peeled is the optical element wafer 10 having a diameter of 4 inches, the damage of the optical element layer 12 caused by the peeling of the epitaxial substrate 11 can be avoided, and the epitaxial substrate 11 can be removed from the optical element layer 12. Stripped quickly and completely. Further, since the ultrasonic horn 40 has the above-described shape, the ultrasonic wave can sufficiently propagate from the inner surface 11d of the outer peripheral edge 11c of the epitaxial substrate 11 to the epitaxial substrate 11, and the efficiency of vibration propagation can be further improved and can be made easier. The optical element layer 12 is transferred to the transfer substrate 20.

Further, the peeling method according to the present invention is not limited to the above embodiment, and the size and shape of the ultrasonic horn 40 shown in the drawing are not limited thereto, and may be in the range in which the effects of the present invention are exerted. Make appropriate changes within.

4‧‧‧Transfer device

11‧‧‧ epitaxial substrate

11a‧‧‧ Surface of the epitaxial substrate

11b‧‧‧ inside the epitaxial substrate

11c‧‧‧ outer periphery of the epitaxial substrate

11d‧‧‧The inside of the outer circumference

11e‧‧‧Outer side of the epitaxial substrate

12‧‧‧Optical element layer

13‧‧‧buffer layer

19‧‧‧ peeling layer

20‧‧‧Transfer substrate

20b‧‧‧Transfer the surface of the substrate

20c‧‧‧Removal of the exposed part of the substrate

25‧‧‧Composite substrate

40‧‧‧Supersonic horn

400‧‧‧天板

400a‧‧‧ inside contact surface

401‧‧‧ side panels

401a‧‧‧The outer side is surrounded by the surface

401b‧‧‧ lower surface of the side panel

402‧‧‧ convex

403‧‧‧Supersonic oscillator

404‧‧‧Mobile means

44‧‧‧Support desk

Claims (2)

A peeling method for shifting an optical element layer of an optical element wafer laminated by an optical element layer to a transfer substrate by a buffer layer formed of GaN on a surface of an epitaxial substrate, wherein the peeling method is The method includes: a transfer substrate bonding process of bonding the transfer substrate via a bonding layer on a surface of the optical element layer of the optical element wafer; and an illumination of the back side of the epitaxial substrate of the optical element wafer to which the transfer substrate is bonded a crystal substrate having pulsed laser light having a permeability and having a wavelength absorbing to the buffer layer, forming a peeling layer forming a peeling layer on the interface between the epitaxial substrate and the buffer layer; after the peeling layer is formed, the use has a surrounding An ultrasonic horn that oscillates an ultrasonic wave in a shape of an outer periphery of the epitaxial substrate, at least contacts the inner surface of the outer periphery, vibrates the epitaxial substrate, peels the epitaxial substrate from the transfer substrate, and causes the optical The element layer is transferred to the optical element layer transfer project of the transfer substrate. An ultrasonic horn for use in the peeling method according to claim 1, comprising: an inner contact surface that forms an arc shape along a periphery of the epitaxial substrate and contacts an inner periphery of the epitaxial substrate; And an outer side surrounding surface surrounding the outer side surface of the epitaxial substrate and determining the position.