JP7253994B2 - How to relocate optical devices - Google Patents

Description

The present invention relates to an optical device transfer method.

An optical device such as an LED (Light Emitting Diode) is formed, for example, by epitaxially growing an n-type semiconductor layer and a p-type semiconductor layer forming a pn junction on the surface of a sapphire substrate. A separation technique called laser lift-off is known for separating the optical device layer thus formed from the sapphire substrate (see Patent Documents 1 and 2). The optical device layer is formed on the sapphire substrate with a buffer layer interposed therebetween. In the laser lift-off method, the sapphire substrate and the optical device layer are separated by irradiating the buffer layer with a laser beam, and the optical device layer is transferred to the transfer substrate.

Japanese Patent Application Laid-Open No. 2004-072052 JP 2016-021464 A

Conventionally, the remnants of the buffer layer destroyed by the laser beam irradiation and the buffer layer remaining attached to the optical device layer without being destroyed are removed by acid cleaning with hydrochloric acid (HCl) after the transfer of the device layer. etc. was removed. However, there are problems such as increased costs due to waste liquid treatment, that waste liquid treatment is dangerous work, and that a washing step is required to remove hydrochloric acid after acid washing, which increases the required time.

The present invention has been made in view of such problems, and an object of the present invention is to provide an optical device that removes the buffer layer remaining on the optical device layer without acid cleaning when the optical device layer is transferred. It is to provide a relocation method.

In order to solve the above-described problems and achieve the object, an optical device transfer method of the present invention provides an optical device transfer substrate for transferring optical devices of an optical device wafer in which an optical device layer is laminated on the surface of an epitaxial substrate with a buffer layer interposed therebetween. a transfer substrate bonding step of bonding a transfer substrate to the surface of an optical device layer of the optical device wafer via a bonding layer to form a composite substrate; and the transfer substrate bonding step. Thereafter, a pulsed laser beam having a wavelength that is transparent to the epitaxial substrate and absorptive to the buffer layer is irradiated from the back surface side of the epitaxial substrate of the optical device wafer that constitutes the composite substrate. a buffer layer breaking step of breaking a layer; and after the buffer layer breaking step, an optical device layer transferring step of peeling the epitaxial substrate from the optical device layer and transferring the optical device layer to a transfer substrate, wherein the optical device After the layer transfer step , irradiate the pulsed laser beam of a wavelength that is absorptive to the buffer layer to the buffer layer remaining in the optical device layer after the epitaxial substrate is peeled off, and remove the remaining buffer layer. It is characterized by performing a buffer layer removing step of removing the buffer layer.

A micro LED forming step of dividing the optical device layer into chip sizes to form micro LEDs may be included before the transfer substrate bonding step.

After the buffer layer removing step, a mounting step of picking up the optical device layer from the transfer substrate and mounting it on a mounting substrate may be included.

The present invention can remove the buffer layer remaining on the optical device layer without acid cleaning when transferring the optical device layer.

FIG. 1 is a perspective view of an optical device wafer including a transfer target of an optical device transfer method according to an embodiment. FIG. 2 is a cross-sectional view of the optical device wafer of FIG. FIG. 3 is a flow chart showing an optical device relocation method according to the embodiment. FIG. 4 is a cross-sectional view showing one state of the transfer substrate bonding step of FIG. FIG. 5 is a sectional view showing one state after FIG. 4 in the transfer substrate bonding step of FIG. 6 is a cross-sectional view showing an example of the buffer layer breaking step of FIG. 3. FIG. FIG. 7 is a cross-sectional view showing one state of the optical device layer transfer step of FIG. FIG. 8 is a cross-sectional view showing an example of the buffer layer removal step of FIG. FIG. 9 is a flowchart showing an optical device relocation method according to the first modification. FIG. 10 is a cross-sectional view of the optical device wafer prior to performing the micro LED formation step of FIG. FIG. 11 is a cross-sectional view showing an example of the micro-LED forming steps of FIG. FIG. 12 is a flow chart showing an optical device relocation method according to the second modification. 13 is a cross-sectional view showing an example of the mounting steps of FIG. 12. FIG. FIG. 14 is a cross-sectional view showing one state after FIG. 13 in the mounting step of FIG.

A form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions, or changes in configuration can be made without departing from the gist of the present invention.

[Embodiment]
A relocation method according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the optical device wafer 1 including the transfer target of the optical device 7 transfer method according to the embodiment will be described. FIG. 1 is a perspective view of an optical device wafer 1 including a transfer target of an optical device 7 transfer method according to an embodiment. FIG. 2 is a cross-sectional view of the optical device wafer 1 of FIG. 1 and 2 schematically show the optical device layer 5 and the like larger than the actual optical device wafer 1 for the sake of explanation of the present embodiment, and the same applies to subsequent drawings. The optical device wafer 1 includes an epitaxial substrate 2 and an optical device layer 5 stacked on the surface 3 side of the epitaxial substrate 2 with a buffer layer 4 interposed therebetween, as shown in FIG.

In this embodiment, the epitaxial substrate 2 is a disk-shaped sapphire substrate having a diameter of approximately 6 inches (approximately 150 mm) and a thickness of approximately 1.2 mm to 1.5 mm. In this embodiment, the optical device layer 5 includes an n-type gallium nitride semiconductor layer 5-1 and a p-type gallium nitride semiconductor layer 5-1 formed on the surface 3 of the epitaxial substrate 2 by an epitaxial growth method to a total thickness of about 6 μm, as shown in FIG. This is the gallium nitride semiconductor layer 5-2. The optical device layer 5 is used, for example, as an LED. In this embodiment, the buffer layer 4 is formed between the surface 3 of the epitaxial substrate 2 and the p-type gallium nitride semiconductor layer 5-2 of the optical device layer 5 when laminating the optical device layer 5 on the epitaxial substrate 2. It is a gallium nitride (GaN) layer having a thickness of about 1 μm.

In this embodiment, the optical device layer 5 is divided into chip sizes and stacked in a plurality of regions partitioned by a plurality of streets 6 intersecting in a grid pattern to form an optical device 7, as shown in FIG. are doing. The spacing between optical device layers 5 , that is, the spacing between optical devices 7 is the same as the width of street 6 . The distance between the optical device layers 5 is about 5 μm in this embodiment. The size of the optical device layer 5 , that is, the size of the optical device 7 is the same as the interval between the streets 6 . The size of the optical device layer 5 is about 10 μm to 20 μm in this embodiment. In the present embodiment, the optical device layer 5 includes approximately 2 million optical devices 7 used as LEDs formed on the epitaxial substrate 2 having a diameter of 6 inches. The epitaxy substrate 2 may be a CMOS (Complementary Metal Oxide Semiconductor) wafer. The chip size of the CMOS device is, for example, about 8 mm to 11 mm, and a plurality of optical device layers 5 are formed on this CMOS device.

Next, a method for relocating the optical device 7 according to the embodiment will be described. FIG. 3 is a flow chart showing a method for relocating the optical device 7 according to the embodiment. The method for transferring the optical device 7 includes, as shown in FIG. 3, a transfer substrate bonding step ST11, a buffer layer breaking step ST12, an optical device layer transferring step ST13, and a buffer layer removing step ST14.

FIG. 4 is a sectional view showing one state of the transfer substrate joining step ST11 of FIG. FIG. 5 is a sectional view showing a state after FIG. 4 in the transfer substrate bonding step ST11 of FIG. The transfer substrate bonding step ST11 is a step of bonding the transfer substrate 11 to the surface of the optical device layer 5 of the optical device wafer 1 via the bonding layer 12 to form the composite substrate 10, as shown in FIGS. be.

Specifically, in the transfer substrate bonding step ST11, first, as shown in FIG. 4, a transfer substrate 11 having the same size as the epitaxial substrate 2 is prepared. An adhesive is applied to one surface of the transfer substrate 11 to form a bonding layer 12 .

In this embodiment, the transfer substrate 11 is preferably a glass substrate having a thickness of about 2.0 mm, which is about the same as the epitaxial substrate 2, but the present invention is not limited to this. As the transfer substrate 11, substrates made of various materials such as metal substrates can be used as long as they can be adhered with a predetermined adhesive.

Moreover, as the adhesive, one containing an organic compound, for example, glue used for adhesive tape is preferably used. Adhesives soften and become less viscous when heated, and when further heated or irradiated with ultraviolet rays, a chemical reaction such as a curing reaction occurs, causing them to harden and further decrease their viscosity. .

In the transfer substrate bonding step ST11, the optical device layer 5 laminated on the epitaxial substrate 2 and the bonding layer 12 of the adhesive applied to the transfer substrate 11 are opposed to each other and brought into contact with each other. In the transfer substrate bonding step ST11, further, from the back surface 8 side of the epitaxial substrate 2 opposite to the front surface 3, toward the transfer substrate 11, or to the bonding layer 12 side of the transfer substrate 11 to which the adhesive is applied. It presses toward the epitaxial substrate 2 from the surface on the opposite side. As a result, in the transfer substrate bonding step ST11, the bonding layer 12 is deformed along the optical device layer 5 so that a part of the optical device layer 5 sinks into the bonding layer 12, as shown in FIG. Thus, in the transfer substrate bonding step ST11, the transfer substrate 11 is bonded to the surface of the optical device layer 5 of the optical device wafer 1 via the bonding layer 12 to form the composite substrate 10. FIG.

In the transfer substrate bonding step ST11, in this embodiment, the bonding layer 12 is bonded with an adhesive so as to have a gap 15 between the optical device layers 5 divided into the chip size of the optical device wafer 1, The optical device layer 5 side of the optical device wafer 1 and the transfer substrate 11 are bonded. Here, in the transfer substrate bonding step ST11, both the pressing force and the temperature during bonding are preferably controlled to such an extent that the gap 15 between the optical device layers 5 is not filled with the adhesive. In addition, in the transfer substrate bonding step ST11, bonding with an adhesive is used in this embodiment, but the present invention is not limited to this, and other bonding methods may be used.

FIG. 6 is a cross-sectional view showing an example of buffer layer breaking step ST12 in FIG. As shown in FIG. 6, the buffer layer breaking step ST12 is, after the transfer substrate bonding step ST11, the epitaxial substrate 2 from the back surface 8 side of the epitaxial substrate 2 of the optical device wafer 1 constituting the composite substrate 10. In this step, the buffer layer 4 is destroyed by irradiating a pulsed laser beam 34 having a wavelength that has an absorptivity to the buffer layer 4 .

Specifically, in the buffer layer breaking step ST12, first, as shown in FIG. , is held by suction on a holding surface 21 of a chuck table 20 connected to a vacuum source (not shown).

In the buffer layer destruction step ST12, next, a laser beam irradiation unit 30 emits a pulsed laser beam 34 from the back surface 8 side of the epitaxial substrate 2 of the composite substrate 10 of the optical device wafer 1 and the transfer substrate 11 held on the chuck table 20. is applied to the buffer layer 4 . The pulsed laser beam 34 is a pulsed laser beam having a wavelength that is transmissive to the epitaxial substrate 2 and absorptive to the buffer layer 4 . As a result, the buffer layer 4 is destroyed in the buffer layer destruction step ST12. In the present embodiment, the buffer layer breaking step ST12 irradiates the entire surface of the epitaxial substrate 2 with the pulsed laser beam 34, but the present invention is not limited to this. In the buffer layer breaking step ST12, only the position of the epitaxial substrate 2 where the buffer layer 4 is formed may be irradiated with the pulse laser beam 34. FIG.

Here, as shown in FIG. 6, the laser beam irradiation unit 30 oscillates the pulsed laser beam 34 of the above-described predetermined wavelength by the laser beam oscillating means 31 . The laser beam irradiation unit 30 uses an optical mirror 32 to change the direction of a pulsed laser beam 34 from a laser beam oscillation means 31 in a direction perpendicular to the rear surface 8 of the epitaxial substrate 2 of the composite substrate 10 held by the chuck table 20 . The laser beam irradiation unit 30 converges the pulsed laser beam 34 from the optical mirror 32 with the condensing lens 33 . The laser beam irradiation unit 30 adjusts the irradiation conditions of the pulsed laser beam 34 in the buffer layer breaking step ST12, such as output and defocus amount.

In the buffer layer breaking step ST12, for example, an ultraviolet laser beam having a repetition frequency of about 50 kHz to 200 kHz and an average output of about 0.1 W to 2.0 W is used as the pulsed laser beam . In the buffer layer destruction step ST12, for example, the spot diameter is set to about 10 μm to 50 μm, the defocus is adjusted to about 1.0 mm to 2.0 mm, and the overlap rate is adjusted to about 20% to 60%, and the buffer layer 4 destruction processing is executed.

FIG. 7 is a cross-sectional view showing an example of the optical device layer transfer step ST13 of FIG. The optical device layer transfer step ST13 is a step of separating the epitaxial substrate 2 from the optical device layer 5 and transferring the optical device layer 5 laminated on the epitaxial substrate 2 to the transfer substrate 11 after the buffer layer breaking step ST12. be.

Specifically, in the optical device layer transfer step ST13, ultrasonic vibration means (not shown) is provided from the back surface 8 side of the epitaxial substrate 2 of the composite substrate 10 whose buffer layer 4 has been destroyed in the buffer layer destruction step ST12. Ultrasonic vibration is applied by a horn. As a result, in the optical device layer transfer step ST13, the epitaxial substrate 2 is separated from the optical device layer 5 starting from the destroyed buffer layer 4, and the optical device layer 5 is transferred to the transfer substrate 11. FIG.

In the optical device layer transfer step ST13, as shown in FIG. 7, the epitaxial substrate 2 is separated from the optical device layer 5, the transfer substrate 11 and the bonding layer 12, whereby the optical device layer 5 (optical device layer 5) transferred to the transfer substrate 11 is removed. 7) protrudes from the bonding layer 12 to form the optical device layer transfer substrate 13 .

FIG. 8 is a cross-sectional view showing an example of the buffer layer removing step ST14. In the buffer layer removing step ST14, as shown in FIG. 8, after the optical device layer transfer step ST13, the buffer layer 4 remaining in the optical device layer 5 is irradiated with a pulsed laser beam 34 having a wavelength having an absorptive property. This is the step of removing the remaining buffer layer 4 .

Specifically, in the buffer layer removal step ST14, as shown in FIG. 8, a laser beam irradiation unit is applied from the optical device layer 5 side of the optical device layer transfer substrate 13 from which the epitaxial substrate 2 has been removed in the optical device layer transfer step ST13. 30 irradiates the remaining buffer layer 4 with a pulsed laser beam 34 . At this time, the surface of the optical device layer transfer substrate 13 on the transfer substrate 11 side is suction-held by the holding surface 21 of the chuck table 20 connected to a vacuum source (not shown). The chuck table 20 is preferably held by suction continuously from the buffer layer breaking step ST12. The pulsed laser beam 34 is a pulsed laser beam with a wavelength that is absorptive to the buffer layer 4 . Thereby, the buffer layer 4 is removed in the buffer layer removing step ST14. Here, the laser beam irradiation unit 30 is preferably the same device as the laser beam irradiation unit 30 used in the buffer layer destruction step ST12.

In the buffer layer removing step ST14, for example, an ultraviolet laser beam having a repetition frequency of about 50 kHz to 200 kHz and an average output of about 0.1 W to 2.0 W is used as the pulse laser beam . In the buffer layer removing step ST14, for example, the spot diameter is adjusted to about 10 μm to 50 μm, the defocus is adjusted to about 1.0 mm to 2.0 mm, and the overlap rate is adjusted to about 20% to 60%, and the buffer layer is removed. 4 removal processing is executed. The repetition frequency, average output, spot diameter, defocus and overlap ratio of the pulsed laser beam 34 in the buffer layer removing step ST14 may be different values from each parameter in the buffer layer destroying step ST12. For example, the average output may be 0.68 W in the buffer layer destroying step ST12 and 0.64 W in the buffer layer removing step ST14. For example, the defocus may be 1.2 mm in the buffer layer destruction step ST12 and 2.0 mm in the buffer layer removal step ST14.

The method for transferring the optical devices 7 of the optical device wafer 1 according to the embodiment includes a transfer substrate bonding step ST11, a buffer layer breaking step ST12, an optical device layer transferring step ST13, and a buffer layer removing step ST14. In the transfer substrate bonding step ST11, the transfer substrate 11 is bonded to the surface of the optical device layer 5 of the optical device wafer 1 via the bonding layer 12 to form the composite substrate 10. FIG. In the buffer layer destruction step ST12, from the back surface 8 side of the epitaxial substrate 2 of the optical device wafer 1 constituting the composite substrate 10, a wavelength which is transparent to the epitaxial substrate 2 and absorptive to the buffer layer 4 is emitted. of the pulsed laser beam 34 to destroy the buffer layer 4 . In the optical device layer transfer step ST13, the epitaxial substrate 2 is separated from the optical device layer 5 and the optical device layer 5 is transferred to the transfer substrate 11 after the buffer layer destruction step ST12. In the buffer layer removal step ST14, the buffer layer 4 remaining in the optical device layer 5 after the optical device layer transfer step ST13 is irradiated with a pulsed laser beam 34 having an absorptive wavelength to remove the remaining buffer layer 4. do.

As a result, the buffer layer 4 can be cleaned by using the same means as the laser beam irradiation means (laser beam irradiation unit 30) used in the buffer layer destruction step ST12 for destroying the buffer layer 4. FIG. Therefore, the process for relocating the optical device 7 can be shortened. In addition, since there is no need to prepare a chemical liquid for acid cleaning, acid cleaning equipment, and waste liquid treatment equipment, it is possible to suppress an increase in cost. In addition, the environmental load caused by acid washing and waste liquid treatment can be reduced.

[First modification]
A relocation method according to the first modification of the embodiment of the present invention will be described. FIG. 9 is a flow chart showing a method for relocating the optical device 7 according to the first modified example. As shown in FIG. 9, the method of transferring the optical device 7 includes a micro LED formation step ST10, a transfer substrate bonding step ST11, a buffer layer destruction step ST12, an optical device layer transfer step ST13, and a buffer layer removal step ST14. ,including. The relocation method according to the modification is the same as the embodiment except for further including a micro LED forming step ST10.

FIG. 10 is a cross-sectional view of the optical device wafer 1 before performing the micro LED formation step ST10 of FIG. FIG. 11 is a cross-sectional view showing an example of the micro LED formation step ST10 of FIG. 10 and 11, the same reference numerals are assigned to the same parts as in the embodiment, and the description thereof is omitted. The micro LED formation step ST10 is a step of dividing the optical device layer 5 into chip sizes to form micro LEDs before the transfer substrate bonding step ST11.

The optical device 7 is a micro LED in a first variant. The optical device layer 5 is in the state before forming the micro LEDs in the first modification. In the first modification, an optical device wafer 1 includes an epitaxial substrate 2 and an optical device layer 5 stacked on the surface 3 side of the epitaxial substrate 2 with a buffer layer 4 interposed therebetween, as shown in FIG.

Specifically, in the micro LED formation step ST10, first, division lines for dividing the optical device layer 5 are set. The line to be divided is a line that coincides with Street 6. As shown in FIG. 11, the laser beam irradiation unit 30 irradiates the optical device layer 5 with a pulsed laser beam 34 along the dividing line. The pulsed laser beam 34 is a pulsed laser beam having a wavelength that is transmissive to the epitaxial substrate 2 and absorptive to the buffer layer 4 . In the micro LED formation step ST10, the pulse laser beam 34 is irradiated along the planned dividing line so as to form the preset width and depth of the streets 6 . The depth of the streets 6 is equal to or greater than the thickness of the optical device layer 5 . Thus, in the micro-LED forming step ST10, the streets 6 are formed in the optical device layer 5, and the optical devices 7, which are micro-LEDs, are formed in the regions partitioned by the streets 6. FIG.

In the micro LED forming step ST10, the streets 6 are formed by laser processing in the first modified example, but the present invention is not limited to this, and other processing methods may be employed. In the micro LED forming step ST10, the streets 6 may be formed by etching using a cutting device, for example.

In the method of transferring the optical devices 7 of the optical device wafer 1 according to the first modification, the optical device layer 5 (optical device 7) is divided into chip sizes to form micro LEDs before the transfer substrate bonding step ST11. An LED forming step ST10 is included. In the case where the optical device 7 is a micro LED, if the buffer layer 4 is removed by acid cleaning, the chemical solution will flow around the side surface of the optical device 7, so there is a risk that not only the buffer layer 4 but also the optical device layer 5 will be removed. be. In the buffer layer removing step ST14, the remaining buffer layer 4 is removed by irradiating the pulsed laser beam 34 with an absorptive wavelength, so that only the buffer layer 4 can be processed. Therefore, removal of the optical device layer 5 and the bonding layer 12 can be suppressed.

[Second modification]
A relocation method according to a second modification of the embodiment of the present invention will be described. FIG. 12 is a flow chart showing a method of relocating the optical device 7 according to the second modification. As shown in FIG. 12, the method of transferring the optical device 7 includes a transferring substrate joining step ST11, a buffer layer breaking step ST12, an optical device layer transferring step ST13, a buffer layer removing step ST14, and a mounting step ST15. include. The relocation method according to the modification is the same as the embodiment except that the mounting step ST15 is further included.

FIG. 13 is a sectional view showing one state of the mounting step ST15 of FIG. FIG. 14 is a sectional view showing a state after FIG. 13 in mounting step ST15 of FIG. 13 and 14, the same reference numerals are assigned to the same parts as in the embodiment, and the description thereof is omitted. The mounting step ST15 is, as shown in FIGS. 13 and 14, a step of picking up the optical device layer 5 from the transfer substrate 11 and mounting it on the mounting substrate 100 after the buffer layer removing step ST14.

Specifically, in the mounting step ST15, first, it is preferable to carry out a stickiness reduction process to reduce the stickiness of the adhesive of the bonding layer 12 that supports the optical device layer 5 (optical device 7). The tackiness reduction treatment is, for example, a treatment to reduce the viscosity of the adhesive by heating the bonding layer 12, or a curing reaction such as a polymerization reaction by irradiating the bonding layer 12 with ultraviolet light or heating to reduce the tackiness of the adhesive. It is a process to lower. The tackiness reduction treatment enables the optical device layer 5 (optical device 7) to be picked up by the pickup unit 50 with a lower force, increases the probability of picking up, and allows the optical device layer 5 (optical device 7) to adhere to the adhesive. is reduced or suppressed.

In the mounting step ST15, next, as shown in FIG. 13, the optical device layer 5 (optical device 7) is gripped or held by suction with the pickup section 51 of the pickup unit 50. FIG. At this time, the surface of the optical device layer transfer substrate 13 on the transfer substrate 11 side is suction-held by the holding surface 21 of the chuck table 20 connected to a vacuum source (not shown). The chuck table 20 may be sucked and held continuously from the buffer layer destruction step ST12. As a result, the transfer substrate 11 and the bonding layer 12 remain on the chuck table 20 and only the optical device layer 5 is picked up by the pickup section 51 of the pickup unit 50 . The pickup unit 51 is arranged and provided at a position facing the optical device layer 5 (optical device 7). Each pickup unit 51 picks up each optical device layer 5 (optical device 7) at an opposing position. In the mounting step ST15, as shown in FIG. 14, each optical device layer 5 (optical device 7) picked up by each pickup section 51 of the pickup unit 50 is mounted on the bonding layer 110 provided on the mounting substrate 100. Move and place. The bonding layers 110 are arranged in the same shape, size, spacing, etc. as the optical device layer 5 (optical device 7).

Each optical device layer 5 (optical device 7) transferred onto the bonding layer 110 of the mounting substrate 100 in the mounting step ST15 is bonded to the mounting substrate 100 via the bonding layer 110 and mounted.

In this manner, in the mounting step ST15, in this embodiment, each optical device layer 5 (optical device 7) protruding from the bonding layer 12 is mounted on the entire surface of the mounting substrate 100 by the pickup sections 51 of the pickup unit 50. Therefore, the optical device layer 5 (optical device 7) can be efficiently transferred. Note that the mounting step ST15 of the present invention is not limited to the second modified example, and the optical device layers 5 (optical devices 7) protruding from the bonding layer 12 are mounted on the mounting board 100 one by one by one pickup unit 51. May be relocated. In this case, the transfer accuracy of each optical device layer 5 (optical device 7) can be improved.

In the method of transferring the optical devices 7 of the optical device wafer 1 according to the second modification, after the buffer layer removing step ST14, the optical device layer 5 (optical device 7) is picked up from the transfer substrate 11 and mounted on the mounting substrate 100. It includes a mounting step ST15.

It should be noted that the present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the gist of the present invention.

REFERENCE SIGNS LIST 1 optical device wafer 2 epitaxial substrate 3 front surface 4 buffer layer 5 optical device layer 7 optical device 8 back surface 10 composite substrate 11 transfer substrate 12 bonding layer 34 pulse laser beam

Claims (3)

An optical device transfer method for transferring an optical device of an optical device wafer in which an optical device layer is laminated on the surface of an epitaxial substrate via a buffer layer to a transfer substrate,
a transfer substrate bonding step of bonding a transfer substrate to the surface of the optical device layer of the optical device wafer via a bonding layer to form a composite substrate;
After the transfer substrate bonding step, a pulsed laser beam having 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 constituting the composite substrate. a buffer layer destruction step of irradiating to destroy the buffer layer;
after the buffer layer breaking step, an optical device layer transfer step of peeling the epitaxial substrate from the optical device layer and transferring the optical device layer to a transfer substrate;
After the optical device layer transfer step , irradiating the pulsed laser beam having a wavelength that is absorptive to the buffer layer to the buffer layer remaining in the optical device layer after the epitaxial substrate is peeled off. and a buffer layer removing step for removing the remaining buffer layer. 2. The optical device transfer method according to claim 1, further comprising a micro LED forming step of dividing the optical device layer into chip sizes to form micro LEDs before the transferring substrate joining step. 3. The optical device transfer method according to claim 1, further comprising a mounting step of picking up the optical device layer from the transfer substrate and mounting it on a mounting substrate after the buffer layer removing step.

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