JP2021012936A - How to relocate optical devices - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for relocating an optical device capable of reliably transferring an optical device from a substrate to a sheet. SOLUTION: This is a method of transferring a plurality of optical devices from an optical device wafer having a plurality of optical devices formed on the surface side of a substrate via a buffer layer, and a plurality of optical devices are transferred to the surface side of the substrate. After performing the sheet sticking step of covering the optical device and sticking the sheet so as to follow the gap between the optical devices and the sheet sticking step, the back surface side of the substrate is transparent to the substrate. The sheet is peeled off from the substrate after performing a buffer layer destruction step and a buffer layer destruction step in which the buffer layer is irradiated with a pulsed laser beam having absorbency to destroy the buffer layer. Includes an optical device transfer step of transferring the optical device to a sheet. [Selection diagram] Fig. 3

Description

The present invention relates to a method of transferring an optical device for transferring a plurality of optical devices from an optical device wafer.

Optical devices typified by LEDs (Light Emitting Diodes) are applied in various fields such as displays, lighting, automobiles, and medical care. For example, an LED is formed by epitaxially growing an n-type semiconductor film and a p-type semiconductor film forming a pn junction on the surface of a substrate made of sapphire or SiC.

The optical device formed on the substrate is separated from the substrate and then mounted on another mounting substrate or the like. As one of the methods for relocating optical devices in this way, a technique called laser lift-off is known. In this laser lift-off, first, an optical device is formed on the surface side of the substrate via a buffer layer. Then, the buffer layer is altered by irradiating a laser beam from the back surface side of the substrate to weaken the bond between the substrate and the optical device, and then the optical device is separated from the substrate and transferred to the transfer destination substrate (transfer substrate). (See Patent Documents 1 and 2).

Further, in recent years, a technology for manufacturing an extremely small LED called a micro LED has also been developed. For example, in a micro LED, a layer (optical device layer) containing various thin films (semiconductor films, etc.) constituting the LED is formed on a substrate, and then the optical device layer is divided into a plurality of fine chips by etching. It is formed (see Patent Document 3).

Japanese Unexamined Patent Publication No. 2004-72052 Japanese Unexamined Patent Publication No. 2016-21464 JP-A-2018-107421

When an optical device such as the above-mentioned micro LED is mounted on a transfer board, the individually separated optical devices are separated from the board and transferred to the transfer board. Specifically, first, the optical device layer formed on the surface side of the substrate is divided into a plurality of fine optical devices, and then a transfer (transfer) sheet is attached to the surface side of the substrate. This sheet is attached so as to be in contact with the upper surface of all optical devices formed on the substrate.

Then, after performing a process of weakening the bond between the substrate and the optical device (alteration of the buffer layer, etc.), the sheet is peeled off from the substrate. As a result, the plurality of optical devices are separated from the substrate and transferred to the sheet. Then, the sheet on which the optical device is transferred is attached to the transfer substrate, and the optical device and the connection electrode formed on the transfer substrate are joined. In this way, the optical device is relocated to the relocation substrate.

However, even if the above-mentioned transfer step of the optical device is performed, some optical devices may remain on the substrate and are not transferred to the sheet. This phenomenon is considered to occur when the sheet is not properly adhered to a plurality of optical devices when the sheet is attached to the substrate, and the adhesion between the sheet and the optical device is insufficient. For example, some optical devices and the sheet may not adhere properly due to an unintended inclination of the holding table that holds the substrate when the sheet is attached or a variation in the thickness of the substrate or the sheet. In this case, even if the sheet is peeled off from the substrate, some optical devices do not follow the tape and remain on the substrate.

If some of the optical devices are not properly transferred to the sheet, it is necessary to redo the transfer process and to pick up the optical devices remaining on the substrate. As a result, the work efficiency of relocating the optical device is reduced.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for transferring an optical device capable of reliably transferring an optical device from a substrate to a sheet.

According to one aspect of the present invention, there is a method for transferring a plurality of optical devices from an optical device wafer including a plurality of optical devices formed on the surface side of a substrate via a buffer layer. After performing the sheet sticking step of covering the plurality of the optical devices on the surface side of the substrate and sticking the sheet so as to follow the gaps between the optical devices, and the sheet sticking step, the substrate A buffer layer destruction step of irradiating the substrate with a pulsed laser beam having transparency to the substrate and absorption to the buffer layer from the back surface side to destroy the buffer layer, and a buffer layer destruction step. A method for relocating an optical device is provided, comprising an optical device transfer step of peeling the sheet from the substrate and transferring a plurality of the optical devices to the sheet.

It is preferable that the sheet is attached to the substrate by thermocompression bonding in the sheet attaching step. Alternatively, preferably, the sheet has a resin layer and an annular adhesive layer corresponding to a region of the substrate on which the optical device is not formed, and in the sheet attaching step, the adhesive layer is said to be The sheet is attached to the substrate so as not to come into contact with the optical device and the resin layer follows the gap between the optical devices.

In the method for transferring an optical device according to one aspect of the present invention, a tape is attached so as to imitate a gap of an optical device formed on a substrate. As a result, the plurality of optical devices are firmly fixed to the sheet, and the plurality of optical devices are surely separated from the substrate when the sheet is peeled off from the substrate. As a result, the optical device can be reliably transferred from the substrate to the sheet.

It is a perspective view which shows the optical device wafer. FIG. 2A is a cross-sectional view showing a manufacturing process of an optical device wafer, and FIG. 2B is a cross-sectional view showing an optical device wafer in a state where the optical device layer is divided into a plurality of optical devices. FIG. 3A is a cross-sectional view showing how the sheet is attached to the substrate, and FIG. 3B is a cross-sectional view showing the substrate to which the sheet is attached. FIG. 4A is a cross-sectional view showing how the other sheet is attached to the substrate, and FIG. 4B is a sectional view showing the substrate to which the other sheet is attached. It is sectional drawing which shows the optical device wafer in the buffer layer breaking step. It is a perspective view which shows the optical device wafer in an optical device transfer step.

Hereinafter, the present embodiment will be described with reference to the accompanying drawings. First, a configuration example of an optical device wafer including a plurality of optical devices that can be relocated by the method of relocating the optical device according to the present embodiment will be described. FIG. 1 is a perspective view showing an optical device wafer 11.

The optical device wafer 11 includes a disk-shaped substrate 13 having a front surface 13a and a back surface 13b. The substrate 13 is divided into a plurality of regions by a plurality of streets 15 arranged in a grid pattern, and optical devices 17 are formed on the surface 13a side of the plurality of regions, respectively. Hereinafter, as an example, a case where the optical device 17 is an LED (Light Emitting Diode) will be described. However, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the optical device 17.

FIG. 2A is a cross-sectional view showing a manufacturing process of the optical device wafer 11. In the manufacturing process of the optical device wafer 11, first, the optical device layer 23 is formed on the surface 13a side of the substrate 13 via the buffer layer 21.

The optical device layer 23 is a layer including various films (semiconductor film, conductive film, insulating film, etc.) constituting the optical device 17 (see FIG. 1). For example, the optical device layer 23 includes a p-type semiconductor film 25 composed of a p-type semiconductor having a large number of holes and an n-type semiconductor film 27 composed of an n-type semiconductor having a large number of electrons. However, the configuration of the optical device layer 23 is appropriately selected according to the structure and function of the optical device 17 finally formed on the substrate 13.

The buffer layer 21 is a layer that suppresses the occurrence of defects due to lattice mismatch between the substrate 13 and the optical device layer 23. The material of the buffer layer 21 is appropriately selected according to the lattice constant between the surface 13a side of the substrate 13 and the lower surface side of the optical device layer 23 (lower surface side of the p-type semiconductor film 25). The buffer layer 21 may be composed of a single-layer film or may be composed of a plurality of laminated films.

The buffer layer 21, the p-type semiconductor film 25, and the n-type semiconductor film 27 are formed on the substrate 13 by, for example, epitaxial growth. In this case, as the substrate 13, an epitaxy substrate capable of epitaxially growing a desired thin film on the substrate 13 is used.

For example, a single crystal substrate made of sapphire, SiC, or the like is used as the substrate 13, and a buffer layer 21 made of GaN, a p-type semiconductor film 25 made of p-type GaN, and an n-type semiconductor film 27 made of n-type GaN are formed on the substrate 13. It is formed by epitaxial growth in order. A MOCVD (Metal Organic Chemical Vapor Deposition) method, an MBE (Molecular Beam Epitaxy) method, or the like can be used to form each film.

Next, the buffer layer 21 and the optical device layer 23 are divided along the street 15. The buffer layer 21 and the optical device layer 23 are divided by, for example, etching. Specifically, first, a mask for etching is formed on the optical device layer 23. The mask is patterned so that the optical device layer 23 is exposed along the street 15.

After that, the etching solution is supplied to the buffer layer 21 and the optical device layer 23 via the mask, and the buffer layer 21 and the optical device layer 23 are etched. As a result, the optical device layer 23 is divided into a plurality of optical devices 17 along the street 15.

FIG. 2B is a cross-sectional view showing an optical device wafer 11 in a state where the optical device layer 23 is divided into a plurality of optical devices 17. When the optical device layer 23 is divided along the street 15, the p-type semiconductor film 25a in which the p-type semiconductor film 25 is fragmented and the n-type semiconductor film 27a in which the n-type semiconductor film 27 is fragmented are separated from each other. A plurality of optical devices 17 are formed. A pn junction is formed by the p-type semiconductor film 25a and the n-type semiconductor film 27a, and the optical device 17 emits light by recombination of holes and electrons.

Further, a buffer layer 21a in which the buffer layer 21 is separated by etching is arranged between the substrate 13 and the optical device 17. That is, each of the optical devices 17 is arranged on the substrate 13 via the buffer layer 21a. The buffer layer 21a corresponds to a layer that is destroyed by irradiation with a laser beam in the buffer layer destruction step described later, and functions as a separation layer for separating the substrate 13 and the optical device 17.

As described above, when etching is used to divide the optical device layer 23, the optical device layer 23 can be finely processed, and an extremely small optical device 17 such as a micro LED can be formed. Then, when the etching of the buffer layer 21 and the optical device layer 23 is completed, the mask formed on the optical device layer 23 is removed.

Note that FIG. 2B shows an optical device 17 including a p-type semiconductor film 25a and an n-type semiconductor film 27a, but the configuration of the optical device 17 is not limited to this. For example, the optical device 17 may further include a light emitting layer between the p-type semiconductor film 25a and the n-type semiconductor film 27a. In this case, holes and electrons are recombined in the light emitting layer, and light is emitted from the light emitting layer. Further, an electrode (connection electrode) for connecting the optical device 17 to another electrode or terminal may be formed on the upper surface side or the lower surface side of the optical device 17.

The plurality of optical devices 17 formed on the substrate 13 are separated from the substrate 13 and then mounted on another mounting substrate or the like. For the transfer of the optical device 17, for example, a sheet for transfer (transfer) is used. Hereinafter, a specific example of a method of relocating the optical device 17 using a sheet will be described.

In the method for transferring optical devices according to the present embodiment, first, a sheet is attached to the surface 13a side of the substrate 13 on which the plurality of optical devices 17 are formed so as to cover the plurality of optical devices 17 (sheet attachment step). ). FIG. 3A is a cross-sectional view showing how the transfer (transfer) sheet (tape, film) 31 is attached to the substrate 13. Hereinafter, as an example, a case where the sheet 31 is attached to the substrate 13 by thermocompression bonding will be described.

In the sheet attaching step, first, the optical device wafer 11 is held by the holding table 10. For example, the holding table 10 is formed in a circular shape in a plan view corresponding to the shape of the optical device wafer 11, and the upper surface of the holding table 10 constitutes a holding surface 10a for holding the optical device wafer 11.

Specifically, the holding table 10 includes a frame body 12 formed in a columnar shape using a metal such as stainless steel (SUS), and a disk-shaped porous member 14 mounted on the upper surface side of the frame body 12. Be prepared. The porous member 14 is made of porous ceramics or the like, and is fitted into a circular recess formed on the upper surface side of the frame body 12. Further, the porous member 14 is connected to a suction source 18 such as an ejector via a flow path 10b formed inside the holding table 10 and a valve 16. The upper surface of the porous member 14 corresponds to a part of the holding surface 10a of the holding table 10 and constitutes a suction surface for sucking the optical device wafer 11.

When the optical device wafer 11 is held by the holding table 10, the optical device wafer 11 is first arranged on the holding table 10. At this time, the optical device wafer 11 is arranged so that the back surface 13b side of the substrate 13 covers the entire upper surface (suction surface) of the porous member 14. In this state, when the negative pressure of the suction source 18 is applied to the holding surface 10a via the valve 16, the flow path 10b, and the porous member 14, the optical device wafer 11 is sucked and held by the holding table 10.

Further, the holding table 10 includes a heating unit (heating means) 20 for heating the optical device wafer 11 inside. For example, the heating unit 20 is composed of a heater or the like, and includes a disk-shaped heating element 22 that generates heat by supplying electric power. The heating element 22 is sandwiched between a disk-shaped metal plate 24 provided on the upper side of the heating element 22 and made of a metal such as aluminum, and a disk-shaped heat insulating member 26 provided on the lower side of the heating element 22. ..

When power is supplied to the heating element 22 while the optical device wafer 11 is held by the holding table 10, the heating element 22 generates heat. Then, the heat generated by the heating element 22 is transferred to the optical device wafer 11 via the metal plate 24, the frame body 12, and the porous member 14, and the optical device wafer 11 is heated. The heat transfer from the heating element 22 to the lower side of the holding table 10 is blocked by the heat insulating member 26.

A sheet 31 for transferring a plurality of optical devices 17 is attached to the optical device wafer 11 held by the holding table 10. For example, the sheet 31 is made of a resin such as polyolefin or polyester, and is attached to the surface 13a side of the substrate 13 on which the plurality of optical devices 17 are formed by thermocompression bonding.

Specifically, first, the sheet 31 is arranged above the surface 13a of the substrate 13 so that the plurality of optical devices 17 and the sheet 31 overlap each other, and the sheet 31 is pressed against the surface 13a of the substrate 13. As a result, the plurality of optical devices 17 come into contact with the sheet 31. When the holding table 10 is heated by the heating unit 20 in this state, the heat of the holding table 10 is transferred to the sheet 31 via the substrate 13 and the sheet 31 is softened. As a result, the plurality of optical devices 17 are embedded in the sheet 31, and the plurality of optical devices 17 and the sheet 31 are joined in close contact with each other.

In this way, the sheet 31 is attached to the substrate 13 by thermocompression bonding. The temperature and time of heating by the heating unit 20 are appropriately set according to the melting point of the sheet 31 and the like. For example, when the sheet 31 made of polyolefin is used, the heating temperature can be set to about 100 ° C. and the heating time can be set to about 1 minute.

FIG. 3B is a cross-sectional view showing the substrate 13 to which the sheet 31 is attached. When the sheet 31 is attached to the substrate 13 by thermocompression bonding, the plurality of optical devices 17 are covered with the sheet 31, and the sheet 31 is deformed so as to follow (along with) the gap between the optical devices 17. More specifically, a plurality of optical devices 17 are each embedded in the sheet 31, and the sheet 31 is not only the upper surface of the optical device 17, but also the side surface of the optical device 17 and the substrate 13 exposed between the optical devices 17. It also comes into contact with the surface 13a.

When the sheet 31 is attached so as to follow the gap between the optical devices 17 in this way, the contact between the sheet 31 and the optical device 17 is compared with the case where the sheet 31 is in contact with only the upper surface of the optical device 17. The area becomes large. As a result, the plurality of optical devices 17 are firmly fixed to the sheet 31.

The sheet 31 may be attached in the decompression chamber. That is, the optical device wafer 11 may be held by the holding table 10 installed in the decompression chamber. In this case, the sheet 31 is carried into the decompression chamber, and the sheet 31 is attached to the substrate 13 under decompression.

Specifically, first, the sheet 31 is pressed against the substrate 13 in a state where the pressure inside the pressure reducing chamber is reduced. Due to the decompression in the chamber, it is possible to prevent gas (air) from entering between the substrate 13 and the sheet 31.

After that, the decompression chamber is opened to the atmosphere, and the atmosphere (air) is introduced into the decompression chamber. As a result, atmospheric pressure acts on the sheet 31, and the sheet 31 is deformed along the shape of the gap between the optical devices 17 and adheres to the surface 13a side of the substrate 13. As a result, the sheet 31 can be attached to the substrate 13 so that a gap is not formed between the sheet 31 and the side surface of the optical device 17 and between the sheet 31 and the surface 13a of the substrate 13.

Although the case where the heat treatment at the time of thermocompression bonding is performed by the heating unit 20 provided inside the holding table 10 has been described above, there is no limitation on the heating method. For example, the heat treatment may be performed by an infrared heater, a warm air heater, a lamp, or the like separately installed above the holding table 10.

Further, although the example in which the sheet 31 is attached by thermocompression bonding has been described above, there are restrictions on the material and the attaching method of the sheet 31 as long as the sheet 31 can be attached so as to follow the gap between the optical devices 17. Absent. FIG. 4A is a cross-sectional view showing how a sheet (tape, film) 33 different from the sheet 31 is attached to the substrate 13.

The sheet 33 is composed of a circular base material 35 formed having substantially the same diameter as the substrate 13, a circular resin layer 37 formed on the lower surface side of the base material 35, and an adhesive adhering to the substrate 13, and the resin layer 37. An annular adhesive layer (glue layer) 39 formed on the lower surface side of the outer peripheral portion of the above is provided. The base material 35 has a higher rigidity than the resin layer 37, and the resin layer 37 is made of a resin that is more flexible than the base material 35. For example, the base material 35 is made of a resin such as polyethylene terephthalate (PET), and the resin layer 37 is made of a flexible resin such as polyolefin (PO) and polyethylene vinyl chloride (PVC).

Further, the adhesive layer 39 is formed so as to correspond to an outer peripheral region (surplus outer peripheral region) in which a plurality of optical devices 17 are not formed in the substrate 13. Specifically, when the sheet 33 is arranged so as to overlap the substrate 13, the adhesive layer 39 is arranged so as to overlap only the outer peripheral excess region of the substrate 13.

When the sheet 33 is attached to the optical device wafer 11, the optical device wafer 11 is first held by the holding table 30. The upper surface of the holding table 30 constitutes a holding surface 30a for holding the optical device wafer 11. The optical device wafer 11 is arranged so that the back surface 13b side of the substrate 13 faces the holding surface 30a of the holding table 30. The configuration of the holding table 30 is not limited as long as the optical device wafer 11 can be held. For example, the holding table 30 is configured in the same manner as the holding table 10 shown in FIGS. 3 (A) and 3 (B).

Next, the sheet 33 is attached to the optical device wafer 11 held by the holding table 30. Specifically, first, the sheet 33 is arranged above the substrate 13 so that the adhesive layer 39 side faces the surface 13a side (optical device 17 side) of the substrate 13. Then, the sheet 33 is pressed against the surface 13a side of the substrate 13 and attached to the substrate 13.

At this time, the adhesive layer 39 of the sheet 33 comes into contact with only the outer peripheral region (surplus outer peripheral region) in which the plurality of optical devices 17 are not formed, and adheres to the substrate 13. Further, the resin layer 37 made of a flexible resin comes into contact with the upper surfaces of the plurality of optical devices 17 and enters the gaps between the optical devices 17.

It is preferable that the sheet 33 is attached in the decompression chamber as in the case of the above-mentioned attachment of the sheet 31 (see FIGS. 3A and 3B). Specifically, the optical device wafer 11 is held by a holding table 30 installed in the decompression chamber. Then, with the pressure inside the pressure reducing chamber being reduced, the sheet 33 is pressed against the substrate 13 while being heated. As a result, the sheet 33 is brought into close contact with the substrate 13 so that a gap is not formed between the resin layer 37 and the side surface of the optical device 17 and between the resin layer 37 and the surface 13a of the substrate 13.

FIG. 4B is a cross-sectional view showing the substrate 13 to which the sheet 33 is attached. When the sheet 33 is attached to the surface 13a side of the substrate 13, the plurality of optical devices 17 are covered with the sheet 33, and the sheet 33 is deformed so as to follow (along with) the gap between the optical devices 17. Specifically, the resin layer 37 of the sheet 33 is deformed and adheres to the optical device 17 so as to follow the gap between the optical devices 17.

As a result, the plurality of optical devices 17 are each embedded in the resin layer 37, and the sheet 33 is not only the upper surface of the optical device 17, but also the side surface of the optical device 17 and the surface 13a of the substrate 13 exposed between the optical devices 17. Also contact. Then, the resin layer 37 and the upper surface and the side surface of the optical device 17 are brought into close contact with each other and are bonded by Van der Waals force.

The sheet 33 includes the adhesive layer 39 only in the region corresponding to the outer peripheral surplus region of the substrate 13. Therefore, even if the sheet 33 is attached to the substrate 13, the adhesive layer 39 does not come into contact with the optical device 17. This makes it possible to prevent a part of the adhesive layer 39 from remaining on the optical device 17 when the optical device 17 and the sheet 33 are finally separated in a later step.

Next, from the back surface 13b side of the substrate 13, a pulsed laser beam having transparency to the substrate 13 and absorption to the buffer layer 21a is irradiated to destroy the buffer layer 21a (buffer layer destruction). Step). FIG. 5 is a cross-sectional view showing the optical device wafer 11 in the buffer layer breaking step.

The buffer layer destruction step is carried out using, for example, a laser processing apparatus 40. The laser processing apparatus 40 includes a holding table 42 that holds the optical device wafer 11, and a laser irradiation unit 44 that irradiates a laser beam toward the optical device wafer 11 held by the holding table 42.

The holding table 42 is formed in a circular shape in a plan view corresponding to, for example, the shape of the optical device wafer 11, and the upper surface of the holding table 42 constitutes a holding surface 42a for holding the optical device wafer 11. Further, the holding surface 42a is connected to a suction source (not shown) such as an ejector via a flow path (not shown) formed inside the holding table 42.

The optical device wafer 11 is arranged on the holding table 42 so that the front surface 13a side (optical device 17 side, sheet 31 side) of the substrate 13 faces the holding surface 42a and the back surface 13b side of the substrate 13 is exposed upward. To. In this state, when the negative pressure of the suction source is applied to the holding surface 42a, the optical device wafer 11 is sucked and held by the holding table 42.

A moving mechanism (not shown) for moving the holding table 42 in the horizontal direction is connected to the holding table 42. The position of the holding table 42 in the horizontal direction is controlled by this moving mechanism. Further, a rotation mechanism (not shown) for rotating the holding table 42 around a rotation axis substantially parallel to the vertical direction is connected to the holding table 42.

A laser irradiation unit 44 is provided above the holding table 42. The laser irradiation unit 44 includes a laser oscillator 46 that pulse-oscillates a laser beam having a predetermined wavelength. As the laser oscillator 46, for example a YAG laser, YVO ₄ laser, YLF laser or the like is used. The laser beam pulse-oscillated by the laser oscillator 46 is reflected by the mirror 48, then enters the condenser lens 50, and is focused by the condenser lens 50 at a predetermined position.

The laser beam 52 is irradiated from the laser irradiation unit 44 toward the optical device wafer 11 held by the holding table 42. The wavelength of the laser beam 52 is set so that the laser beam 52 has transparency to the substrate 13 and absorbs to the buffer layer 21a. Therefore, the laser irradiation unit 44 irradiates the optical device wafer 11 with the laser beam 52 that passes through the substrate 13 and is absorbed by the buffer layer 21a.

In the buffer layer destruction step, first, the holding table 42 holding the optical device wafer 11 is positioned under the condenser lens 50. Then, the laser beam 52 is irradiated from the laser irradiation unit 44 toward the back surface 13b side of the substrate 13.

The laser beam 52 passes through the substrate 13 and is irradiated to one buffer layer 21a, and is absorbed by the buffer layer 21a. As a result, the buffer layer 21a is destroyed, and the bonding between the optical device 17 and the substrate 13 in contact with the destroyed buffer layer 21a is weakened. The irradiation conditions (power, spot diameter, repetition frequency, focusing position, etc.) of the laser beam 52 are appropriately set within a range in which the buffer layer 21a can be destroyed.

The focusing point of the laser beam 52 is positioned inside or near the buffer layer 21a, for example. However, the focusing position of the laser beam 52 is not limited as long as the buffer layer 21a can be destroyed.

Further, in the buffer layer destruction step, it is not always necessary to completely remove the buffer layer 21a to completely separate the substrate 13 and the optical device 17. Specifically, when the sheet 31 is peeled from the substrate 13 in the optical device transfer step described later, the optical device 17 and the substrate 13 are separated from the substrate 13 to the extent that the optical device 17 follows the sheet 31 and is separated from the substrate 13. The bond should be weakened.

For example, in the buffer layer destruction step, the laser beam 52 is irradiated to the buffer layer 21a to form a altered layer (altered layer) in the buffer layer 21a, and the bond between the optical device 17 and the substrate 13 is weakened. This altered layer corresponds to a layer (separation layer) that triggers separation when the optical device 17 is separated from the substrate 13. However, the mode of destruction of the buffer layer 21a is not limited to this, and the substrate 13 and the optical device 17 may be completely separated by adjusting the irradiation conditions of the laser beam 52.

After that, the laser beam 52 is similarly irradiated to the other buffer layer 21a. As a result, all the buffer layers 21a are destroyed, and the coupling between the substrate 13 and the plurality of optical devices 17 is weakened.

Next, the sheet 31 is peeled off from the substrate 13 and the plurality of optical devices 17 are transferred to the sheet 31 (optical device transfer step). FIG. 6 is a perspective view showing the optical device wafer 11 in the optical device transfer step. In the optical device transfer step, the sheet 31 is moved in a direction away from the substrate 13 while the substrate 13 is fixed. As a result, the sheet 31 is peeled off from the surface 13a side of the substrate 13.

Immediately before the sheet 31 is peeled off, the sheet 31 is attached so as to follow the gap between the optical devices 17 and is in close contact with the upper surface and the side surface of the optical device 17 (FIGS. 3 (B) and 4 (B)). )reference). Further, the buffer layer 21a (see FIG. 5 and the like) is destroyed, fragile, or removed by the buffer layer destruction step described above. Therefore, when the sheet 31 is peeled off from the substrate 13, the plurality of optical devices 17 follow the sheet 31 and are separated from the substrate 13 and transferred to the sheet 31 as shown in FIG.

There are no restrictions on the method of peeling the sheet 31. For example, the end portion of the sheet 31 may be gripped with a gripping tool to peel off the sheet 31. Further, after the peeling tape is attached to the sheet 31 to integrate the sheet 31 and the peeling tape, the peeling tape may be peeled from the substrate 13 together with the sheet 31.

Further, when the sheet 31 is peeled off, a process for promoting the peeling may be carried out. For example, the separation between the substrate 13 and the sheet 31 may be promoted by applying ultrasonic vibration to the substrate 13. Further, a sharp tool such as a cutter or tweezers may be inserted into the interface between the substrate 13 and the sheet 31 to partially peel off the substrate 13 and the sheet 31. Further, a gas such as air may be injected from the side of the substrate 13 toward the interface between the substrate 13 and the sheet 31 to promote the separation between the substrate 13 and the sheet 31.

As described above, in the method for relocating the optical device according to the present embodiment, the sheet 31 (or the sheet 33) is attached so as to follow the gap between the optical devices 17 formed on the substrate 13. As a result, the plurality of optical devices 17 are firmly fixed to the sheet 31, and when the sheet 31 is peeled off from the substrate 13, the plurality of optical devices 17 are surely separated from the substrate 13. As a result, the optical device 17 can be reliably transferred from the substrate 13 to the sheet 31.

The plurality of optical devices 17 transferred to the sheet 31 are transferred to, for example, another substrate (transfer substrate) on which the optical device 17 is planned to be mounted, and bonded. In the present embodiment, the sheet 31 on which the plurality of optical devices 17 are transferred is attached to the transfer substrate, and the plurality of optical devices 17 are bonded to the transfer substrate (bonding step). As a result, the bonding of the plurality of optical devices 17 can be performed at once.

Specifically, first, a substrate (mounting substrate) on which a plurality of optical devices 17 are mounted is prepared. A plurality of electrodes connected to the optical device 17 are formed on the surface of the mounting substrate. Here, a case where the arrangement of the plurality of electrodes included in the mounting substrate corresponds to the arrangement of the plurality of optical devices 17 (see FIG. 6) embedded in the sheet 31 will be described.

In the bonding step, first, the optical device 17 and the electrodes of the mounting substrate are bonded to the exposed surfaces of the plurality of optical devices 17 embedded in the sheet 31 and the exposed surfaces of the plurality of electrodes formed on the mounting substrate. Apply the adhesive. The material of the bonding agent is not limited, and for example, Sn—Cu-based solder that electrically connects the optical device 17 and the electrodes of the mounting substrate can be used.

Next, the surface on which the electrodes of the mounting substrate are formed and the surface of the sheet 31 where the optical device 17 is exposed face each other, and the sheet 31 is attached to the mounting substrate. As a result, the plurality of optical devices 17 are bonded to the electrodes of the mounting substrate via the bonding agent, and the plurality of optical devices 17 are bonded together. After that, when the sheet 31 is peeled off from the mounting substrate, the plurality of optical devices 17 are separated from the sheet 31 in a state of being bonded to the mounting substrate.

If the arrangement of the plurality of optical devices 17 embedded in the sheet 31 is different from the arrangement of the plurality of electrodes provided on the mounting substrate, the distance between the optical devices 17 can be adjusted by pulling and expanding the sheet 31. You may. Specifically, as the sheet 31, a tape that can be expanded (stretched) by applying an external force is used. Then, the above-mentioned sheet sticking step, buffer layer breaking step, and optical device transfer step are carried out using this sheet 31.

After that, the distance between the optical devices 17 is increased by expanding the sheet 31. The expansion amount of the sheet 31 at this time is adjusted so that the arrangement of the plurality of optical devices 17 corresponds to the arrangement of the plurality of electrodes formed on the transfer substrate. Then, by attaching the expanded sheet 31 to the mounting board, a plurality of optical devices 17 are collectively mounted on the mounting board.

In addition, the structure, method, etc. according to the above-described embodiment can be appropriately modified and implemented as long as the scope of the object of the present invention is not deviated.

11 Optical device wafer 13 Substrate 13a Front surface 13b Back surface 15 Street 17 Optical device 21 Buffer layer 21a Buffer layer 23 Optical device layer 25 p-type semiconductor film 25a p-type semiconductor film 27 n-type semiconductor film 27an-type semiconductor film 31 sheet (tape, the film)
33 sheets (tape, film)
35 Base material 37 Resin layer 39 Adhesive layer (glue layer)
10 Holding table 10a Holding surface 10b Flow path 12 Frame body 14 Porous member 16 Valve 18 Suction source 20 Heating unit (heating means)
22 Heat generator 24 Metal plate 26 Insulation member 30 Holding table 30a Holding surface 40 Laser processing device 42 Holding table 42a Holding surface 44 Laser irradiation unit 46 Laser oscillator 48 Mirror 50 Condensing lens 52 Laser beam

Claims (3)

A method for transferring a plurality of optical devices from an optical device wafer having a plurality of optical devices formed on the surface side of a substrate via a buffer layer.
A sheet attachment step of covering a plurality of the optical devices and attaching a sheet to the surface side of the substrate so as to follow the gaps between the optical devices.
After performing the sheet attaching step, a pulsed laser beam having transparency to the substrate and absorption to the buffer layer is irradiated from the back surface side of the substrate to irradiate the buffer layer. The buffer layer destruction step to destroy and
A method for transferring an optical device, which comprises performing the buffer layer breaking step, then peeling the sheet from the substrate, and transferring a plurality of the optical devices to the sheet. The method for transferring an optical device according to claim 1, wherein in the sheet attaching step, the sheet is attached to the substrate by thermocompression bonding. The sheet has a resin layer and an annular adhesive layer corresponding to a region of the substrate on which the optical device is not formed.
The sheet attaching step is characterized in that the sheet is attached to the substrate so that the adhesive layer does not come into contact with the optical device and the resin layer follows the gap between the optical devices. The method for relocating an optical device according to claim 1.