Device manufacturing method

Abstract

The present invention provides a device manufacturing method capable of suppressing damage to an optical device layer when peeling from a substrate. The device manufacturing method comprises: a tape pasting step (101) of pasting a stretchable tape on the front surface of an optical device layer of an optical device wafer; a splitting starting point forming step (102) of positioning a focal point inside the optical device layer and irradiating a laser beam with a wavelength that is transparent to the optical device layer, thereby forming a splitting starting point; a buffer layer destruction step (103) of irradiating a laser beam with a wavelength that is transparent to the epitaxial substrate and absorptive to the buffer layer from the back side of an epitaxial substrate of the optical device wafer, thereby destroying the buffer layer; a peeling step (104) of peeling the epitaxial substrate from the optical device layer; and a splitting step (105) of splitting the optical device layer along the splitting starting point by applying an external force to the tape.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a device. Background Art

[0002] Optical device wafers, such as LEDs (Light Emitting Diodes), are formed by epitaxially growing n-type and p-type semiconductors forming a pn junction on the surface of a substrate such as sapphire (Al2O3) or silicon carbide (SiC). Laser lift-off is a known technique for removing the optical device layer formed in this manner from the substrate (see Patent Document 1). In laser lift-off, a buffer layer near the interface between the substrate and the optical device layer is irradiated with a laser beam to form a modified layer. This modified layer is then used to separate the substrate from the optical device layer, allowing the optical device layer to be transferred to a mounting substrate.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-72052

[0004] Furthermore, when manufacturing LEDs (sub-100μm square) known as μLEDs, which have been attracting attention in recent years, the optical device layer is separated by etching before being transferred to a transfer substrate using laser lift-off. However, when the laser beam is applied to the etched μLED, the laser beam also reaches the portion where the optical device layer has been removed by etching, causing damage such as chipping and cracking due to heat and other factors. Summary of the Invention

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a device capable of suppressing damage to an optical device layer during separation of a substrate.

[0006] In order to solve the above-mentioned problems and achieve the purpose, the device manufacturing method of the present invention transfers the optical device layer of an optical device wafer stacked with an optical device layer via a buffer layer on the front surface of an epitaxial substrate to a transfer component to manufacture an LED device, and is characterized in that the device manufacturing method includes the following steps: a tape pasting step, pasting a stretchable tape on the front surface of the optical device layer of the optical device wafer; a splitting starting point forming step, before or after the tape pasting step, positioning the focal point inside the optical device layer and irradiating a laser beam with a wavelength that is transparent to the optical device layer to form a splitting starting point; a buffer layer destroying step, after the tape pasting step and the splitting starting point forming step, irradiating a laser beam with a wavelength that is transparent to the epitaxial substrate and absorptive to the buffer layer from the back side of the epitaxial substrate of the optical device wafer to destroy the buffer layer; a peeling step, after the buffer layer destroying step, peeling the epitaxial substrate from the optical device layer; and a splitting step, after the peeling step, applying external force to the tape to split the optical device layer along the splitting starting point.

[0007] The present invention can prevent damage to the optical device layer when peeling from the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a perspective view showing an example of an optical device wafer to be processed in the device manufacturing method according to the embodiment.

[0009] Figure 2 yes Figure 1 A cross-sectional view of an optical device wafer is shown.

[0010] Figure 3 This is a flowchart showing the flow of a method for manufacturing a device according to an embodiment.

[0011] Figure 4 It shows Figure 2 A perspective view showing an example of the pasting steps shown.

[0012] Figure 5 It shows Figure 2 A perspective view of an example of the step of forming a division starting point is shown.

[0013] Figure 6 Shown in partial section Figure 2 A side view showing one state of the dividing starting point forming step is shown.

[0014] Figure 7 Shown in partial section Figure 2 A side view of one state of the buffer layer destruction step is shown.

[0015] Figure 8 Shown in partial section Figure 2 A side view showing one state of the peeling step is shown.

[0016] Figure 9 Shown in partial section Figure 2 A side view showing one state of the segmentation step is shown.

[0017] Figure 10 Shown in partial section Figure 2 The segmentation steps shown Figure 9 A side view of the next state.

[0018] Figure 11 This is a flowchart showing the flow of a method for manufacturing a device according to a modification.

[0019] Figure 12 Shown in partial section Figure 11 A side view showing one state of the dividing starting point forming step is shown.

[0020] Description of labels

[0021] 1: Optical device wafer; 10: Epitaxial substrate; 11: Front side; 12: Back side; 20: Buffer layer; 30: Optical device layer; 31: n-type gallium nitride semiconductor layer; 32: p-type gallium nitride semiconductor layer; 33: Front side; 34: Spacer; 35: LED device; 36: Shield tunnel (division starting point); 40: Belt; 50, 60: Laser beam; 51, 61: Focusing points. DETAILED DESCRIPTION

[0022] The modes (embodiments) for implementing the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the structural elements of the present embodiments described below include contents that can be easily imagined by those skilled in the art, as well as substantially the same contents. Moreover, the structures described below can be appropriately combined. In addition, various omissions, replacements or changes in the structure can be made without departing from the scope of the present invention.

[0023] [Implementation Method]

[0024] A device manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. First, the structure of an optical device wafer 1 to be processed according to the embodiment will be described. Figure 1 This is a perspective view showing an example of an optical device wafer 1 to be processed in the device manufacturing method according to the embodiment. Figure 2 yes Figure 1 The optical device wafer 1 shown in FIG. 1 includes an epitaxial substrate 10, a buffer layer 20, and an optical device layer 30. In addition, in order to illustrate the embodiment, Figure 2 , the buffer layer 20 and the optical device layer 30 are schematically shown larger than the actual size with respect to the optical device wafer 1 , and the same applies to the subsequent drawings.

[0025] In the embodiment, epitaxial substrate 10 is a disk-shaped sapphire substrate having a diameter of about 4 inches (about 100 mm) and a thickness of about 1.2 mm to 1.5 mm. Optical device layer 30 is formed on front surface 11 of epitaxial substrate 10 via buffer layer 20 .

[0026] Alternatively, the epitaxial substrate 10 may be, for example, a CMOS (Complementary Metal Oxide Semiconductor) wafer. The chip size of a CMOS device is, for example, approximately 8 mm to 11 mm. When the epitaxial substrate 10 is a CMOS wafer, multiple optical device layers 30 are formed on the CMOS device.

[0027] In this embodiment, the buffer layer 20 is a gallium nitride (GaN) layer having a thickness of approximately 1 μm. When the optical device layer 30 is stacked on the epitaxial substrate 10, the buffer layer 20 is formed near the interface between the epitaxial substrate 10 and the optical device layer 30. More specifically, the buffer layer 20 is formed between the front surface 11 of the epitaxial substrate 10 and the p-type gallium nitride semiconductor layer 32 of the optical device layer 30, which will be described later.

[0028] The optical device layer 30 is stacked on the front surface 11 side of the epitaxial substrate 10 via the buffer layer 20. The optical device layer 30 includes an n-type gallium nitride semiconductor layer 31 and a p-type gallium nitride semiconductor layer 32. The n-type gallium nitride semiconductor layer 31 is stacked on the front surface 33 side of the optical device layer 30 relative to the p-type gallium nitride semiconductor layer 32. The p-type gallium nitride semiconductor layer 32 is stacked on the buffer layer 20 side relative to the n-type gallium nitride semiconductor layer 31. In the embodiment, the optical device layer 30 is formed by epitaxial growth to a total thickness of approximately 6 μm and a maximum thickness of approximately 10 μm. In the embodiment, the optical device layer 30 is used as a μLED.

[0029] In the embodiment, the optical device layer 30 includes a plurality of grid-like streets 34 arranged on the front surface 33, and LED devices 35 formed in the regions defined by the streets 34. The optical device layer 30 is divided along the streets 34 to produce the LED devices 35. The spacing between the LED devices 35 is the same as the width of the streets 34, which is approximately 5 μm in the embodiment. The size of the LED devices 35 is the same as the spacing between the streets 34, which is approximately 10 μm to 20 μm in the embodiment.

[0030] Next, a method for manufacturing the device according to the embodiment will be described. Figure 3 10. This is a flowchart showing the flow of a device manufacturing method according to an embodiment. The device manufacturing method according to an embodiment includes a tape applying step 101, a separation starting point forming step 102, a buffer layer destroying step 103, a peeling step 104, and a separation step 105.

[0031] (with pasting step 101)

[0032] Figure 4 It shows Figure 2 1 is a perspective view of an example of the tape sticking step 101. The tape sticking step 101 is a step of sticking the tape 40 on the front surface 33 of the optical device layer 30 of the optical device wafer 1.

[0033] The tape 40 has stretchability and includes, for example, a base layer formed of a stretchable synthetic resin and a paste layer laminated on the base layer and formed of a stretchable and adhesive synthetic resin.

[0034] like Figure 4As shown, in the tape attaching step 101 of the embodiment, first, tape 40 is attached to the back side of an annular frame 41. The annular frame 41 has an opening that is larger than the outer diameter of the optical device wafer 1. In the tape attaching step 101, the optical device wafer 1 is then positioned at a predetermined position within the opening of the annular frame 41, and the front side 33 of the optical device layer 30 is attached to the tape 40. This secures the optical device wafer 1 to the annular frame 41 and the tape 40.

[0035] (Division Starting Point Formation Step 102)

[0036] Figure 5 It shows Figure 2 A perspective view of an example of the division starting point forming step 102 is shown. Figure 6 Shown in partial section Figure 2 The figure shows a side view of a state of the separation starting point forming step 102. Separation starting point forming step 102 is a step in which a focal point 51 is positioned inside the optical device layer 30 and a laser beam 50 having a wavelength that is transparent to the optical device layer 30 is irradiated to form the separation starting point. Separation starting point forming step 102 can be performed before or after the tape applying step 101. In this embodiment, separation starting point forming step 102 is performed after the tape applying step 101.

[0037] like Figure 5 and Figure 6 As shown, in the division starting point forming step 102 of the embodiment, a shield tunnel 36 serving as a division starting point of the optical device layer 30 is formed using a laser processing apparatus 300. The laser processing apparatus 300 includes a chuck table 310, a laser beam irradiation unit 320, an imaging unit 330, and a moving unit 340 for relatively moving the chuck table 310 and the laser beam irradiation unit 320.

[0038] In the splitting starting point forming step 102, first, the front surface 33 side of the optical device layer 30 of the optical device wafer 1 is sucked and held by the holding surface 311 of the chuck table 310 through the tape 40, and the outer periphery of the annular frame 41 is fixed by the clamping member 312. Then, the laser beam irradiation unit 320 is moved to the processing position by the moving unit 340. Then, the optical device wafer 1 and the front surface 11 (refer to Figure 2 ) side is photographed to detect the streets 34. After the streets 34 are detected, alignment is performed to align the streets 34 with the irradiation portion of the laser beam irradiation unit 320.

[0039] Here, if Figure 6As shown, the laser beam irradiation unit 320 includes a laser oscillator 321, an optical mirror 322, and a focusing lens 323. The laser beam irradiation unit 320 oscillates a pulsed laser beam 50 of a predetermined wavelength using the laser oscillator 321. The laser beam irradiation unit 320 uses the optical mirror 322 to change the direction of the laser beam 50 oscillated by the laser oscillator 321 to a direction perpendicular to the back surface 12 of the epitaxial substrate 10 of the optical device wafer 1 held by the chuck table 310. The laser beam irradiation unit 320 uses the focusing lens 323 to focus the laser beam 50 reflected by the optical mirror 322. The laser beam irradiation unit 320 adjusts the irradiation conditions of the laser beams 50 and 60, such as the output and frequency, in the division starting point formation step 102 and the buffer layer destruction step 103 described later.

[0040] In the division starting point forming step 102, the focal point 51 is positioned inside the optical device layer 30, and the optical device layer 30 is irradiated with a pulsed laser beam 50 having a wavelength that is transparent to the optical device layer 30. In the division starting point forming step 102 of the embodiment, the pulsed laser beam 50 having a wavelength that is also transparent to the epitaxial substrate 10 is irradiated from the back surface 12 side of the epitaxial substrate 10. In the division starting point forming step 102 of the embodiment, a shield tunnel 36 composed of a pore and an amorphous material that shields the pore is formed in the thickness direction inside the optical device layer 30.

[0041] In the division starting point forming step 102, the laser beam 50 is irradiated along the streets 34 of the optical device layer 30 while the laser beam irradiation unit 320 is moved relative to the chuck table 310. Within the optical device layer 30, pores and the amorphous material formed around the pores grow from the vicinity of the focal point 51 toward the front surface 33, forming shield tunnels 36 at predetermined intervals along the region corresponding to the streets 34. By adjusting the repetition frequency and feed speed of the laser beam 50, the shield tunnels 36 are formed so that adjacent amorphous materials are connected to each other.

[0042] In addition, in the division starting point forming step 102 , the processing conditions of the laser beam 50 are set as follows, for example.

[0043] Wavelength: 1064nm

[0044] Repetition frequency: 10kHz

[0045] Average output: 0.1W

[0046] Feed speed: 100mm / s

[0047] Spot diameter: 0.5μm~3μm

[0048] (Buffer Layer Destruction Step 103)

[0049] Figure 7 Shown in partial section Figure 2 The buffer layer destruction step 103 is shown in a side view. The buffer layer destruction step 103 is a step of irradiating the back surface 12 of the epitaxial substrate 10 of the optical device wafer 1 with a laser beam 60 having a wavelength that is transparent to the epitaxial substrate 10 and absorptive to the buffer layer 20, thereby destroying the buffer layer 20. The buffer layer destruction step 103 is performed after the tape application step 101 and the separation starting point formation step 102.

[0050] like Figure 7 As shown, in the buffer layer destruction step 103 of the embodiment, the buffer layer 20 formed near the interface between the epitaxial substrate 10 and the optical device layer 30 is destroyed using a laser processing device 300. The laser processing device 300 used in the buffer layer destruction step 103 may be the same as the laser processing device 300 used in the division starting point formation step 102, or may be a different device.

[0051] In the buffer layer destruction step 103, first, similar to the separation starting point formation step 102, the front surface 33 side of the optical device layer 30 of the optical device wafer 1 is suction-held by the holding surface 311 of the chuck table 310 via the tape 40, and the outer periphery of the annular frame 41 is fixed by the clamping member 312. If the buffer layer destruction step 103 is performed immediately after the separation starting point formation step 102, this step can be omitted because the optical device wafer 1 is already fixed to the chuck table 310.

[0052] In the buffer layer destruction step 103, the focal point 61 is then positioned within the buffer layer 20, and a pulsed laser beam 60 having a wavelength that is transparent to the epitaxial substrate 10 and absorptive to the buffer layer 20 is irradiated from the back surface 12 of the epitaxial substrate 10. In the buffer layer destruction step 103, the buffer layer 20 is destroyed by irradiating the buffer layer 20 with the laser beam 60. In the buffer layer destruction step 103, the entire surface of the epitaxial substrate 10 is irradiated with the laser beam 60.

[0053] In the buffer layer destruction step 103 , processing conditions of the laser beam 60 are set, for example, as follows.

[0054] Wavelength: 257nm

[0055] Repetition frequency: 50kHz~200kHz

[0056] Average output: 0.1W~2W

[0057] Spot diameter: 10μm~50μm

[0058] (Peeling Step 104)

[0059] Figure 8 Shown in partial section Figure 2 FIG. 1 is a side view showing a state of the peeling step 104. The peeling step 104 is a step of peeling the epitaxial substrate 10 from the optical device layer 30. The peeling step 104 is performed after the buffer layer destruction step 103.

[0060] like Figure 8 As shown, after the buffer layer destruction step 103, the buffer layer 20 of the optical device wafer 1 is removed. Therefore, in the peeling step 104, the epitaxial substrate 10 can sometimes be naturally peeled from the optical device layer 30. In cases where peeling is difficult, the epitaxial substrate 10 can be peeled by applying external force, such as by applying ultrasonic waves using a known method or inserting a wedge between the epitaxial substrate 10 and the optical device layer 30.

[0061] (Segmentation Step 105)

[0062] Figure 9 Shown in partial section Figure 2 A side view of one state of the segmentation step 105 is shown. Figure 10 Shown in partial section Figure 2 The segmentation step 105 shown Figure 9 The dividing step 105 is a step of dividing the optical device layer 30 along the dividing starting point by applying an external force to the tape 40. The dividing step 105 is performed after the peeling step 104.

[0063] like Figure 9 and Figure 10 As shown, in the separating step 105 of the embodiment, an expansion device 400 is used to apply an external force to the tape 40 in a radial direction, thereby separating the optical device wafer 1. The expansion device 400 includes a chuck table 401, a clamping member 402, a lifting unit 403, a lifting member 404, and a roller member 405. The lifting member 404 is cylindrical and coaxially arranged on the outer periphery of the chuck table 401. The roller member 405 is rotatably arranged on the same plane as or slightly above the holding surface of the chuck table 401 and is located at the upper end of the lifting member 404.

[0064] like Figure 9 As shown, in the dividing step 105, the front surface 33 side of the optical device layer 30 is first placed on the holding surface of the chuck table 401 via the tape 40, and the outer periphery of the annular frame 41 is fixed by the clamping member 402. At this time, the roller member 405 contacts the tape 40 between the inner edge of the annular frame 41 and the outer edge of the optical device layer 30.

[0065] like Figure 10As shown, in the segmentation step 105, the chuck table 401 and the lifting member 404 are then raised integrally by the lifting unit 403. At this time, the outer periphery of the belt 40 is fixed by the clamping member 402 via the annular frame 41, so that the portion between the inner edge of the annular frame 41 and the outer edge of the optical device layer 30 expands in the surface direction. Furthermore, the roller member 405 provided at the upper end of the lifting member 404 mitigates friction with the belt 40, so that the entire belt 40 expands in the surface direction. At this time, the cross-section of the belt 40 between the inner edge of the annular frame 41 and the outer edge of the optical device layer 30 becomes a straight line from the lower surface of the annular frame 41 toward the upper surface of the roller member 405.

[0066] In the segmentation step 105, as a result of the expansion of the strip 40, a tensile force acts radially on the strip 40. When the radial tensile force acts on the strip 40, as shown in FIG. Figure 10 As shown, the optical device layer 30, to which the tape 40 is attached, is separated into chip-sized pieces for each LED device 35, with the shield tunnels 36 along the lanes 34 serving as the starting point for separation. After the optical device layer 30 is separated into chip-sized LED devices 35, the LED devices 35 are picked up from the tape 40 using a known picker, for example, in a picking process.

[0067] [Variation]

[0068] Next, a method for manufacturing a device according to a modification example will be described. Figure 11 2 is a flowchart showing the flow of a device manufacturing method according to a modified example. The device manufacturing method according to the modified example includes a separation starting point forming step 201 , a tape attaching step 202 , a buffer layer destroying step 203 , a peeling step 204 , and a separation step 205 .

[0069] (Division Starting Point Formation Step 201)

[0070] Figure 12 Shown in partial section Figure 11 The figure shows a side view of a state of the separation starting point forming step 201. Similar to the separation starting point forming step 102 of the embodiment, separation starting point forming step 201 positions the focal point 51 within the optical device layer 30 and irradiates the optical device layer 30 with a laser beam 50 having a wavelength that is transparent to the optical device layer 30, thereby forming the separation starting point. In the modified example, separation starting point forming step 201 is performed before the tape applying step 202.

[0071] like Figure 12 As shown, in the division starting point forming step 201 of the modification, similarly to the division starting point forming step 102 of the embodiment, the shield tunnel 36 serving as the division starting point of the optical device layer 30 is formed using the laser processing apparatus 300 .

[0072] In the separation starting point forming step 201 of the modified example, the back surface 12 of the epitaxial substrate 10 of the optical device wafer 1 is first held by suction using the holding surface 311 of the chuck table 310, and then secured to the chuck table 310. Next, the laser beam irradiation unit 320 is moved to the processing position by the movement unit 340. Next, the imaging unit 330 images the front surface 33 of the optical device layer 30 of the optical device wafer 1 to detect the streets 34. After the streets 34 are detected, alignment is performed to align the streets 34 with the irradiation portion of the laser beam irradiation unit 320.

[0073] In the segmentation starting point forming step 201 of the modified example, a light-converging point 51 is positioned inside the optical device layer 30 from the front surface 33 side of the optical device layer 30, and a pulsed laser beam 50 having a wavelength that is transparent to the optical device layer 30 is irradiated. In the segmentation starting point forming step 201 of the modified example, a shield tunnel 36 composed of a pore and an amorphous material shielding the pore is formed in the thickness direction inside the optical device layer 30.

[0074] In the segmentation starting point forming step 201 of the modified example, similarly to the segmentation starting point forming step 102 of the embodiment, the laser beam 50 is irradiated along the streets 34 of the optical device layer 30 while the laser beam irradiation unit 320 is moved relative to the chuck table 310. Within the optical device layer 30, pores and the amorphous material formed around the pores grow from the vicinity of the focal point 51 toward the front surface 33, forming amorphous shield tunnels 36 at predetermined intervals along the region corresponding to the streets 34.

[0075] (From pasting step 202 to splitting step 205)

[0076] The tape applying step 202 of the modified example is identical to the tape applying step 101 of the embodiment, except that the shield tunnel 36 is already formed in the optical device layer 30 when the tape 40 is applied to the front surface 33 of the optical device layer 30. Therefore, a description thereof will be omitted. Furthermore, the buffer layer destroying step 203, the peeling step 204, and the dividing step 205 of the modified example are identical to the buffer layer destroying step 103, the peeling step 104, and the dividing step 105 of the embodiment. Therefore, a description thereof will be omitted.

[0077] As described above, in the device manufacturing methods of the embodiment and the modified example, the optical device layer 30 is pre-irradiated with the laser beam 50 to form a division starting point within the optical device layer 30. After the optical device layer 30 is peeled off from the epitaxial substrate 10, the optical device layer 30 is expanded and divided into chip-sized LED devices 35. Specifically, because the division starting point is formed within the optical device layer 30, the interior of the optical device layer 30 is not exposed when the buffer layer 20 is destroyed and the epitaxial substrate 10 is peeled off. Furthermore, no regions are formed where the optical device layer 30 and the buffer layer 20 are absent. Therefore, even when the entire surface of the buffer layer 20 is irradiated with the laser beam 60, damage to the optical device layer 30 can be suppressed. Consequently, in the manufacture of μLED devices, a decrease in quality and yield due to damage can be suppressed.

[0078] The present invention is not limited to the above-described embodiment, and can be implemented with various modifications within the scope of the present invention.

[0079] For example, in the segmentation starting point forming steps 102 and 201, the shield tunnel 36 is formed as the segmentation starting point in the embodiment and the modified example. However, in the present invention, a modified layer formed by stealth cutting can also be formed as the segmentation starting point. A modified layer refers to a region whose density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area. Examples of modified layers include melt-processed regions, cracked regions, dielectric breakdown regions, refractive index change regions, and regions where these regions are mixed. The mechanical strength and other characteristics of the modified layer are lower than those of other parts of the optical device layer 30.

[0080] In the division starting point forming step 102 , the laser beam 50 is irradiated from the back surface 12 of the epitaxial substrate 10 in the embodiment. However, in the present invention, the laser beam 50 may be irradiated from the front surface 33 of the optical device layer 30 via the tape 40 .

[0081] In addition, in the splitting starting point forming step 201, in a modified example, the back side 12 of the epitaxial substrate 10 is directly attracted and held on the chuck worktable 310, but in the present invention, a tape can also be pasted on the back side 12 to hold the epitaxial substrate 10 on the chuck worktable 310 via the tape.

Claims

1. A device manufacturing method for manufacturing an LED device by transferring an optical device layer of an optical device wafer having an optical device layer stacked on a front surface of an epitaxial substrate with a buffer layer interposed therebetween onto a transfer member, characterized in that: The manufacturing method of the device comprises the following steps: a tape pasting step of pasting a stretchable tape on the front surface of the optical device layer of the optical device wafer; a separation starting point forming step of positioning a focusing point inside the optical device layer and irradiating the optical device layer with a laser beam having a wavelength that is transparent to the optical device layer, thereby forming a separation starting point, before or after the tape attaching step; a buffer layer destruction step, after the tape attaching step and the division starting point forming step, irradiating the back side of the epitaxial substrate of the optical device wafer with a laser beam having a wavelength that is transparent to the epitaxial substrate and absorptive to the buffer layer, thereby destroying the buffer layer; a peeling step of peeling the epitaxial substrate from the optical device layer after the buffer layer destruction step; and A dividing step, after the peeling step, applying an external force to the tape to divide the optical device layer along a dividing starting point.

Images