JP2003098977A - Method of transferring element, method of arraying element and method of manufacturing image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer method of elements which makes efficient transfer possible and is suitable for mass production. SOLUTION: In transferring the elements arrayed on a first substrate onto a second substrate, the elements are previously arrayed across a photocatalyst layer and an organic matter layer on the first substrate and are irradiated with UV rays, by which the elements are peeled from the first substrate. A transparent substrate through which the UV rays transmit is used as the first substrate. The photocatalyst layer contains, for example, titanium oxide as a material containing a photocatalyst effect. The organic matter layer contains, for example, a polyimide as organic matter. The irradiation with the UV rays is efforted by using a UV lamp unit and the elements to be transferred are simultaneously irradiated with the UV rays in correspondence thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element transfer method, and further to an element array method and an image display device manufacturing method to which the element transfer method is applied.

[0002]

2. Description of the Related Art For example, when light emitting elements are arranged in a matrix and assembled into an image display device, conventionally, a liquid crystal display device (LCD: Liquid Crystal Display) or a plasma display panel (PDP: Plasma Display Panel) is used.
As described above, an element is directly formed on the substrate, or a single LED package is arranged like a light emitting diode display (LED display). For example, in an image display device such as an LCD or a PDP, since the elements cannot be separated, it is usual that the respective elements are formed at intervals from the pixel pitch of the image display device from the beginning of the manufacturing process.

On the other hand, in the case of an LED display, L
The ED chip is taken out after dicing, individually connected to external electrodes by wire bonding or bump connection by flip chip, and packaged. In this case, the pixels are arranged at a pixel pitch as an image display device before or after packaging, and this pixel pitch is independent of the element pitch at the time of element formation.

LED (light emitting diode) which is a light emitting element
Is expensive, it is possible to reduce the cost of the image display device using LEDs by manufacturing many LED chips from one wafer. That is, the price of the image display device can be reduced by changing the conventional LED chip size of about 300 μm square to an LED chip of several tens μm square and connecting the LED chips to manufacture the image display device.

[0005]

When an image display device is manufactured by the transfer technique as described above, it is necessary to transfer only the elements to be transferred selectively and surely.
Further, efficient transfer and accurate transfer are also required.

Under the circumstances, the applicant of the present application has already proposed a transfer technique using laser ablation. The transfer technology using this laser ablation is
For example, a polyimide film is formed on a glass substrate, elements are arranged on this, and at the time of transfer, an excimer laser is irradiated to ablate the polyimide film to separate the glass substrate.

However, in the transfer technique using the laser ablation, the excimer laser itself is very expensive, the maintenance cost and the running cost are great, and the laser irradiation range of 1 m is large.
Since it is as narrow as about m × 1 mm, there is still a problem that it takes a very long time for processing, which is an unsuitable technique when considering mass production. In addition, the irradiation of the excimer laser has a drawback that the element may be damaged depending on the irradiation energy.

The present invention has been proposed in view of such conventional circumstances, and provides a novel element transfer method suitable for mass production, which enables efficient transfer, can reduce running cost. The purpose is to It is another object of the present invention to provide a device transfer method that does not damage the device. A further object of the present invention is to provide a method for arranging elements and a method for manufacturing an image display device, which is an application of the above-mentioned transfer method and takes advantage of the advantages of the transfer method.

[0009]

In order to achieve the above-mentioned object, the transfer method of the present invention is a transfer method of an element in which elements arranged on a first substrate are transferred to a second substrate. The element is arranged on the first substrate through the photocatalyst layer and the organic material layer, and the element is separated from the first substrate by irradiating with ultraviolet rays.

When ultraviolet rays are irradiated in a state where the photocatalyst layer and the organic material layer are in contact with each other, the photocatalyst exerts a catalytic action to decompose the organic material. As a result, peeling occurs at the interface between the photocatalyst layer and the organic material layer, and the elements arranged on the organic material layer are peeled from the first substrate and transferred to the second substrate side. Here, by irradiating with ultraviolet rays, a large area can be collectively processed, and a short-time processing is realized. Further, since the photocatalyst layer does not change before and after the transfer process, it can be repeatedly used.

The element arraying method of the present invention is an element arraying method of rearranging a plurality of elements arrayed on a first substrate on a second substrate, wherein the elements are arrayed on the first substrate. The first transfer step in which the element is transferred so that the element is held in the temporary holding member so that the element is separated from the held state, and the element held in the temporary holding member is further separated. A second transfer step of transferring onto the second substrate, and in at least one of the first transfer step and the second transfer step, the element is held on the first substrate or temporarily via the photocatalyst layer and the organic material layer. It is characterized in that the above elements are separated from the first substrate or the temporary holding member by arranging them on the working member and irradiating them with ultraviolet rays. In the above arraying method, the transfer of the elements is efficiently and surely performed while maintaining the advantages of the above transfer method, so that the enlarged transfer for increasing the distance between the elements is smoothly performed.

Furthermore, in the method of manufacturing the image display device of the present invention, in the method of manufacturing the image display device in which the light emitting elements are arranged in a matrix, it is separated from the state in which the light emitting elements are arranged on the first substrate. And a second transfer step in which the light emitting element held by the temporary holding member is further separated from the first transfer step of transferring the light emitting element so as to be in a state and holding the light emitting element by the temporary holding member. A second transfer step of transferring the light-emitting element onto the first substrate or the temporary holding member through the photocatalyst layer and the organic material layer in at least one of the first transfer step and the second transfer step. The light-emitting element is peeled off from the first substrate or the temporary holding member by irradiating with ultraviolet rays.

According to the method of manufacturing the image display device, the light emitting elements are arranged in a matrix and the image display portion is constituted by applying the transfer method and the arrangement method. Therefore, the light emitting elements that are formed in a dense state, that is, the degree of integration is increased and the fine processing is performed, are efficiently rearranged, and the productivity is significantly improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A method for transferring elements, a method for arranging elements, and a method for manufacturing an image display device to which the present invention is applied will be described in detail below with reference to the drawings.

In the transfer method of the present invention, in order to transfer an element, as shown in FIG. 1 (a), a photocatalyst layer 2 is formed on a transfer source substrate 1 and an organic material layer 3 is interposed on the photocatalyst layer 2. The elements 4 to be transferred are arranged in advance. Transfer source substrate 1
Can be made of any material or form, such as glass, resin, or film, as long as it can transmit ultraviolet rays. The photocatalyst layer 2 may be made of any material as long as it has a photocatalytic action, and examples thereof include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), and tungsten oxide (WO ₃ ). ), Bismuth oxide (Bi ₂ O ₃ ), strontium titanate (SrTiO ₃ ) and the like can be used. Of these, titanium oxide is preferable. Organic layer 3
May be any as long as it is decomposed by the catalytic action of the photocatalyst layer 2, and examples thereof include polyimide. The inventor has confirmed that decomposition occurs in polyimide.

On the other hand, an adhesive layer 6 is formed in advance on the transfer destination substrate 5 onto which the element 4 is transferred, and the adhesive layer 6 contacts the element 4 as shown in FIG. like,
The transfer destination substrate 5 is superposed on the transfer source substrate 1. Various adhesives such as epoxy resin can be used for the adhesive layer 6, and the thickness thereof is arbitrary.

After the transfer destination substrate 5 is superposed on the transfer source substrate 1, a UV lamp unit 7 is arranged on the back side of the transfer source substrate 1 as shown in FIG. The UV lamp unit 7 is prepared to have a size capable of covering the required area. The UV lamp unit 7 may be irradiated with energy capable of decomposing organic substances at a minimum, so that the illuminance distribution may not be particularly uniform.

When the UV lamp unit 7 is used to irradiate ultraviolet rays, the action of the photocatalyst layer 2 decomposes the organic material layer 3 in a portion in contact with the photocatalyst layer 2. Then, peeling occurs at the interface between the photocatalyst layer 2 and the organic material layer 3, and the photocatalyst layer 2
Remains on the transfer source substrate 1, and the element 4 moves to the transfer destination substrate 5. Therefore, as shown in FIG. 1D, if the transfer source substrate 1 is removed, as a result, the element 4 is transferred from the transfer source substrate 1 to the transfer destination substrate 5. here,
Since the photocatalyst layer 2 on the transfer source substrate 1 has no change before and after the transfer process, it can be reused repeatedly by washing, for example.

According to the above transfer method, a large area can be processed at a time in a short time, so that a transfer process having a very high throughput can be realized. For example,
The size of the substrate to be processed may be any size as long as the UV lamp unit 7 can emit ultraviolet rays. Moreover, since efficient transfer can be realized only with an inexpensive equipment such as a UV lamp unit,
It is possible to reduce equipment investment and running costs. Further, compared to the case where an excimer laser is used, the element is less likely to be damaged, and the yield can be significantly improved.

The above-mentioned transfer method can be applied to, for example, a method of arranging elements in which a light emitting element is embedded in a resin to form a chip component, then enlarged and transferred and rearranged, a method of manufacturing an image display device, and the like. Hereinafter, a method of arranging the elements and a method of manufacturing the image display device will be described.

For example, when an image display device is manufactured using light emitting diodes, it is necessary to arrange the light emitting diodes so as to be spaced apart from each other. There are various methods for this arrangement, but here, the two-step expansion transfer method will be described as an example. In the two-step magnifying transfer method, first, the elements formed on the first substrate with a high degree of integration are transferred to the temporary holding member so that the elements are separated from the state in which the elements are arranged on the first substrate. Then, two-step enlargement transfer is performed in which the element held by the temporary holding member is further separated and transferred onto the second substrate. Although the transfer is performed in two steps in this example, the transfer can be performed in three steps or in multiple steps depending on the degree of enlargement in which the elements are arranged apart from each other.

FIG. 2 is a diagram showing the basic steps of the two-step expansion transfer method. First, the first substrate 20 shown in FIG.
Elements 22 such as light emitting elements are densely formed thereon. By forming the elements densely, the number of elements generated on each substrate can be increased, and the product cost can be reduced. The first substrate 20 is, for example, a semiconductor wafer,
Various substrates such as a glass substrate, a quartz glass substrate, a sapphire substrate, and a plastic substrate can be formed, but each element 22 may be directly formed on the first substrate 20, or formed on another substrate. It may be an array of the created ones.

Next, as shown in FIG. 2B, the elements 22 from the first substrate 20 to the temporary holding member 2 shown by broken lines in the figure.
1, and each element 2 is transferred onto the temporary holding member 21.
2 is retained. The adjacent elements 22 are now separated,
They are arranged in a matrix as shown. Ie element 2
2 is transferred so as to widen the spaces between the elements also in the x direction, but is also transferred so as to widen the spaces between the elements also in the y direction perpendicular to the x direction. The distance separated at this time is
The distance is not particularly limited, and as an example, the distance can be set in consideration of the formation of the resin portion and the formation of the electrode pad in the subsequent process. All the elements on the first substrate 20 may be transferred while being separated from each other when the first substrate 20 is transferred onto the temporary holding member 21. In this case, the size of the temporary holding member 21 may be equal to or larger than the size obtained by multiplying the number of elements 22 arranged in a matrix (in the x direction and the y direction) by the distance. In addition, the temporary holding member 11
It is also possible that a part of the elements on the first substrate 20 are transferred on the upper portion while being spaced apart from each other.

After such a first transfer step, as shown in FIG. 2C, the elements 22 existing on the temporary holding member 21 are separated from each other. The resin is covered and the electrode pad is formed. The resin coating around the element is formed for facilitating the formation of the electrode pad and facilitating the handling in the next second transfer step. As will be described later, the electrode pad is formed after the second transfer step in which the final wiring is continued, so that the electrode pad is formed in a relatively large size so that wiring failure does not occur at that time. The electrode pads are not shown in FIG. 2 (c). A resin-formed chip 24 is formed by covering each element 22 with the resin 23. Element 22
Is located substantially in the center of the resin-formed chip 24 on a plane,
It may be present at a position deviated to one side or a corner side.

Next, as shown in FIG. 2D, a second transfer process is performed. In this second transfer process, the elements 22 arranged in a matrix on the temporary holding member 21 are transferred onto the second substrate 25 so as to be further separated together with the resin-formed chips 24. Also in the second transfer step, the adjacent element 22
Are separated from each other by the resin forming chips 24 and arranged in a matrix as shown in the drawing. That is, the elements 22 are transferred so as to widen the distance between the elements in the x direction, but are also transferred so as to widen the distance between the elements also in the y direction perpendicular to the x direction. Assuming that the positions of the elements arranged in the second transfer step correspond to the pixels of the final product such as an image display device, approximately an integer multiple of the pitch between the original elements 22 is arranged in the second transfer step. It is the pitch of the elements 22. Here, when the enlargement ratio of the pitch separated from the first substrate 20 to the temporary holding member 21 is n and the expansion ratio of the pitch separated from the temporary holding member 21 to the second substrate 25 is m, an approximately integral multiple The value E of is expressed by E = n × m.

Wiring is provided to each element 22 separated from the resin-formed chip 24 on the second substrate 25. This time,
Wiring is performed by using the electrode pad or the like previously formed while suppressing connection failure as much as possible. This wiring is, for example, the element 22.
Is a light emitting element such as a light emitting diode, a p electrode,
Including wiring to the n-electrode.

In the two-step expansion transfer method shown in FIG.
Is the electrode pad using the separated space after the first transfer.
Can be performed, and can be created after the second transfer.
Lines are applied, but using the electrode pads etc. that were previously formed
Wiring is performed while suppressing connection failures as much as possible. Therefore,
The yield of the image display device can be improved. Well
Also, in the two-step expansion transfer method of this example, the distance between the elements
There are two steps to separate the elements.
Actually, by performing the multi-step expansion transfer that separates
The number of transfers will be reduced. That is, for example, here
Temporary holding members 21, 21a from the first substrate 20, 20a
The expansion ratio of the pitches separated by 2 is set to 2 (n = 2)
Separated from the holding members 21 and 21a on the second substrate 25
Assuming that the pitch expansion rate is 2 (m = 2), the
If you try to transfer to the area enlarged by copying,
The rate is 4 times 2 × 2, and the square of that is 16 times of transfer.
Then, it becomes necessary to perform alignment of the first substrate 16 times.
However, in the two-step expansion transfer method of this example, the number of alignment
Is the square of the enlargement factor of 2 in the first transfer process 4 times and the second transfer process
A total of 8 if you simply add 4 times the power of 2
It only needs to be done once. That is, when the same transfer magnification is intended,
In the case of (n + m)^Two= N^Two+ 2nm + m ^TwoAnd
Therefore, be sure to reduce the transfer count by 2 nm.
You can do it. Therefore, the number of manufacturing processes is
And saves money, especially when the expansion rate is large.
Become.

In the two-step enlargement transfer method shown in FIG. 2, the element 22 is, for example, a light emitting element, but is not limited to this, and other elements such as a liquid crystal control element, a photoelectric conversion element, a piezoelectric element, and a thin film transistor. Element, thin film diode element, resistance element, switching element, micro magnetic element,
It may be an element selected from minute optical elements or a portion thereof, or a combination thereof.

In the second transfer step, the light emitting element is treated as a resin-formed chip and transferred from the temporary holding member to the second substrate. Refer to FIGS. 3 and 4 for this resin-formed chip. Explain. The resin-formed chip 30 is a light-emitting element 31 that is spaced apart and is solidified with resin 32 around the light-emitting element 31. Such a resin-formed chip 30 has the light-emitting element 31 on the second substrate from the temporary holding member. It can be used when transferring. The resin-formed chip 30 has a substantially flat plate shape, and its main surface has a substantially square shape. The shape of the resin-formed chip 30 is a shape formed by solidifying a resin 32. Specifically, an uncured resin is applied to the entire surface so as to include each light emitting element 31, and the edge is formed after the resin is cured. It is a shape obtained by cutting the portion by dicing or the like.

Electrode pads 33 and 34 are formed on the front surface side and the back surface side of the substantially flat resin 32, respectively. The electrode pads 33, 34 are formed on the entire surface by the electrode pads 33, 3
It is formed by forming a conductive layer such as a metal layer or a polycrystalline silicon layer which is a material of No. 4, and patterning it into a required electrode shape by a photolithography technique. These electrode pads 33 and 34 are formed so as to be connected to the p electrode and the n electrode of the light emitting element 31, respectively, and via holes or the like are formed in the resin 32 if necessary.

Here, the electrode pads 33 and 34 are formed on the front surface side and the back surface side of the resin-formed chip 30, respectively, but it is possible to form both electrode pads on one surface, for example, in the case of a thin film transistor. Since there are three electrodes of a source, a gate, and a drain, three or more electrode pads may be formed. Electrode pad 33,
The position of 34 is deviated on the flat plate so that the contacts do not overlap even if the contacts are taken from the upper side in the final wiring formation. The shape of the electrode pads 33, 34 is not limited to the square shape, and may be another shape.

By constructing such a resin-formed chip 30, the periphery of the light emitting element 31 is covered with the resin 32 so that the electrode pads 33 and 34 can be accurately formed by flattening and the area is wider than that of the light emitting element 31. Electrode pad 3
3, 34 can be extended, and handling is facilitated when the transfer in the next second transfer step is advanced by the suction jig. As will be described later, since the final wiring is performed after the subsequent second transfer step, the electrode pads 33, 34 having a relatively large size are formed.
By using the wiring, wiring failure can be prevented.

Next, FIG. 5 shows the structure of a light emitting element as an example of an element used in the two-step expansion transfer method of this example. 5A is an element cross-sectional view, and FIG. 5B is a plan view. This light emitting element is a GaN-based light emitting diode, for example, an element that is crystal-grown on a sapphire substrate. In such a GaN-based light emitting diode, laser ablation occurs due to laser irradiation through the substrate, and film peeling occurs at the interface between the sapphire substrate and the GaN-based growth layer due to the phenomenon of nitrogen vaporization of GaN. It has a feature that element isolation can be facilitated.

First, regarding the structure, a hexagonal pyramidal GaN layer 42 that is selectively grown is formed on a base growth layer 41 made of a GaN-based semiconductor layer. An insulating film (not shown) is present on the underlying growth layer 41, and the hexagonal pyramidal GaN layer 42 is MOCVD-formed in the opening of the insulating film.
It is formed by the method. The GaN layer 42 is a pyramid-shaped growth layer covered with the S-plane (1-101 plane) when the main surface of the sapphire substrate used during growth is the C-plane, and is a region doped with silicon. is there. This G
The inclined S-plane portion of the aN layer 42 functions as a clad having a double hetero structure. An InGaN layer 43, which is an active layer, is formed so as to cover the inclined S-plane of the GaN layer 42, and a magnesium-doped GaN layer 44 is formed outside thereof.
Is formed. This magnesium-doped GaN layer 44
Also functions as a clad.

In such a light emitting diode, the p electrode 4
5 and the n-electrode 46 are formed. The p electrode 45 is Ni / Pt formed on the magnesium-doped GaN layer 44.
/ Au or Ni (Pd) / Pt / Au. The n-electrode 46 is formed by vapor-depositing a metal material such as Ti / Al / Pt / Au at the opening of the insulating film (not shown). The underlying growth layer 41
When taking out the n-electrode from the back side of the
Is unnecessary on the front surface side of the underlying growth layer 41.

The GaN-based light emitting diode having such a structure is an element capable of emitting blue light, and can be separated from the sapphire substrate relatively easily by laser ablation, and a laser beam is selectively irradiated. As a result, selective peeling is realized. The GaN-based light emitting diode may have a structure in which an active layer is formed on a flat plate or in a strip shape, or may have a pyramidal structure in which a C plane is formed at an upper end portion. Further, it may be another nitride-based light emitting device, a compound semiconductor device, or the like.

Next, a specific method for manufacturing an image display device to which the light emitting element arranging method shown in FIG. 2 is applied will be described. As the light emitting element, the GaN-based light emitting diode shown in FIG. 5 is used. First, as shown in FIG.
A plurality of light emitting diodes 52 are densely formed on the main surface of. The size of the light emitting diode 52 may be minute, and may be, for example, about 20 μm on each side. As a constituent material of the first substrate 51, a material having a high transmittance with respect to the wavelength of the laser with which the light emitting diode 52 is irradiated, such as a sapphire substrate, is used. Although the p-electrode and the like are formed in the light emitting diode 52, the final wiring is not yet formed, and the groove 52g for separating the elements is formed, so that the individual light emitting diodes 52 can be separated. The formation of the groove 52g is performed by reactive ion etching, for example.

Next, the light emitting diode 52 on the first substrate 51 is transferred onto the first temporary holding member 53. Here, as an example of the first temporary holding member 53, a glass substrate,
A quartz glass substrate, a plastic substrate, or the like can be used. In this example, the quartz glass substrate was used. A release layer 54 that functions as a release layer is formed on the surface of the first temporary holding member 53. For the release layer 54, a fluorine coat, a silicone resin, a water-soluble adhesive (for example, polyvinyl alcohol: PVA), polyimide, or the like can be used, but here, polyimide is used.

At the time of transfer, as shown in FIG. 6, an adhesive (for example, an ultraviolet curable adhesive) 55 sufficient to cover the light emitting diode 52 is applied on the first substrate 51, and is supported by the light emitting diode 52. Thus, the first temporary holding member 53 is superposed. In this state, as shown in FIG. 7, the adhesive 55 is irradiated with ultraviolet rays (UV) from the back surface side of the first temporary holding member 53 to cure it. The first temporary holding member 53 is a quartz glass substrate, and the ultraviolet rays pass through this to quickly cure the adhesive 55.

At this time, the first temporary holding member 53 is
Since it is supported by the light emitting diode 52,
The distance between the first substrate 51 and the first temporary holding member 53 is
It depends on the height of the light emitting diode 52.
As shown in FIG. 7, if the adhesive 55 is cured with the first temporary holding member 53 being superposed so as to be supported by the light emitting diode 52, the thickness t of the adhesive 55 becomes the first substrate. It is regulated by the distance between 51 and the first temporary holding member 53, and is regulated by the height of the light emitting diode 52. That is, the light emitting diode 52 on the first substrate 51 functions as a spacer, and the adhesive layer having a certain thickness serves as the first substrate 51 and the first temporary holding member 5.
3 will be formed. As described above, in the above method, the thickness of the adhesive layer is determined by the height of the light emitting diode 52, so that it is possible to form the adhesive layer having a constant thickness without strictly controlling the pressure.

After the adhesive 55 is cured, the light emitting diode 52 is irradiated with a laser from the back surface of the first substrate 51 as shown in FIG.
Peeling from 1 using laser ablation. Ga
The N-based light-emitting diode 52 decomposes into metallic Ga and nitrogen at the interface with sapphire, and therefore can be peeled off relatively easily. An excimer laser, a harmonic YAG laser, or the like is used as a laser for irradiation. By the peeling using the laser ablation, the light emitting diode 52 is separated at the interface of the first substrate 51 and is transferred onto the temporary holding member 53 in a state of being embedded in the adhesive 55.

FIG. 9 shows a state in which the first substrate 51 is removed by the above peeling. At this time, the GaN-based light-emitting diode is peeled off from the first substrate 51 made of a sapphire substrate by a laser, and Ga 56 is deposited on the peeled surface, so it is necessary to etch this. Therefore, wet etching is performed with an aqueous solution of NaOH or dilute nitric acid, and as shown in FIG.
Remove 56. Further, as shown in FIG. 11, the surface is cleaned by oxygen plasma (O ₂ plasma), the adhesive 55 is cut by the dicing groove 57 by dicing, and each light emitting diode 52 is diced, and then the light emitting diode 52 is selectively separated. Do. As the dicing process, dicing using a normal blade and laser processing using the above laser are performed when a narrow cut of 20 μm or less is required. The cut width is the light emitting diode 52 covered with the adhesive 55 in the pixel of the image display device.
Although it depends on the size of, the groove shape is processed by an excimer laser to form the shape of the chip.

To selectively separate the light emitting diodes 52,
First, as shown in FIG. 12, a thermoplastic adhesive 58 is applied onto the cleaned light emitting diode 52, and a second temporary holding member 59 is placed thereon. As the second temporary holding member 59, a glass substrate, a quartz glass substrate, a plastic substrate, or the like can be used for the second temporary holding member 53, and the quartz glass substrate is used in this example. Further, a photocatalyst layer 60 made of titanium oxide or the like and a peeling layer 61 made of polyimide or the like are formed on the surface of the second temporary holding member 59.

Next, as shown in FIG. 13, the laser is irradiated from the back surface side of the first temporary holding member 53 only to the position corresponding to the light emitting diode 52a to be transferred, and the light emitting diode 52a is subjected to laser ablation. The first
The temporary holding member 53 is peeled off. At the same time, visible or infrared laser light is radiated from the back side of the second temporary holding member 59 to the position corresponding to the light emitting diode 52a which is also the transfer target, and the thermoplastic adhesive 58 in this portion is temporarily removed. Melt and cure. After that, when the second temporary holding member 59 is peeled off from the first temporary holding member 53, as shown in FIG. 14, only the light emitting diode 52a to be transferred is selectively separated, and the second temporary holding member 59 is separated. The image is transferred onto the temporary holding member 59. At this time, a photocatalyst layer may be formed on the surface of the first temporary holding member 53 and the light emitting diode 52a may be peeled off by irradiation of ultraviolet rays (UV light), but here, selective irradiation is performed. It uses easy laser ablation.

After the selective separation, as shown in FIG. 15, resin is applied to cover the transferred light emitting diode 52 to form a resin layer 62. Further, as shown in FIG. 16, the thickness of the resin layer 62 is reduced by oxygen plasma or the like.
As shown in FIG. 7, a via hole 63 is formed at a position corresponding to the light emitting diode 52 by laser irradiation. An excimer laser, a harmonic YAG laser, a carbon dioxide laser, or the like can be used to form the via hole 63. At this time, the via hole 63 has a diameter of, for example, about 3 to 7 μm.

Next, the anode side electrode pad 64 connected to the p electrode of the light emitting diode 52 through the via hole 63 is formed. The anode side electrode pad 64 is
For example, it is formed of Ni / Pt / Au or the like. FIG. 18 shows a state in which the light emitting diode 52 is transferred to the second temporary holding member 59, the via hole 63 on the anode electrode (p electrode) side is formed, and then the anode side electrode pad 64 is formed.

After forming the anode side electrode pad 64, the third side is formed to form the cathode side electrode on the opposite surface.
Is transferred to the temporary holding member 65. The third temporary holding member 65 is also made of, for example, quartz glass, and the photocatalytic layer 66 is formed on the surface thereof. At the time of transfer, as shown in FIG. 19, an adhesive agent 67 is applied on the light emitting diode 52 having the anode side electrode pad 64 formed thereon, and further on the resin layer 62, and the third temporary holding member 65 is attached thereon. Can match. When UV light is irradiated from the back surface side of the second temporary holding member 59 in this state, the interface between the photocatalyst layer 60 formed on the second temporary holding member 59 made of quartz glass and the peeling layer 61 made of polyimide. Then, peeling occurs due to decomposition of the organic matter, and the light emitting diode 52 and the resin layer 62 formed on the peeling layer 61 are transferred onto the third temporary holding member 65. FIG. 20 shows a state in which the second temporary holding member 59 is separated.

When forming the cathode side electrode,
After the transfer process, O shown in FIG. _TwoBy plasma treatment
By removing the release layer 61 and the excess resin layer 62,
The contact semiconductor layer (n electrode) of the ion 52 is exposed.
Let The light emitting diode 52 is bonded to the temporary holding member 65.
Held by the agent 67, the light emitting diode 52
The back surface of the is on the n-electrode side (cathode electrode side)
If the electrode pad 68 is formed as shown in FIG.
The pad 68 is electrically connected to the back surface of the light emitting diode 52.
Be done.

After that, the electrode pad 68 is patterned. The electrode pad on the cathode side at this time is, for example, about 6
It can be 0 μm square. As the electrode pad 68, a transparent electrode (ITO, ZnO type, etc.) or Ti / Al
A material such as / Pt / Au is used. In the case of a transparent electrode, even if the back surface of the light emitting diode 52 is largely covered, light emission is not blocked, so that the patterning accuracy is rough, a large electrode can be formed, and the patterning process is facilitated.

Next, the light emitting diodes 52 solidified by the resin layer 62 and the adhesive 67 are individually cut out to obtain the resin-formed chip. The cutting may be performed by laser dicing, for example. FIG. 23 shows a cutting process by laser dicing. Laser dicing is performed by irradiating a laser line beam, and the resin layer 62 and the adhesive 67 are cut until the photocatalyst layer 66 on the third temporary holding member 65 is exposed. By this laser dicing, each light emitting diode 5
2 is cut out as a resin-formed chip of a predetermined size,
The process is moved to the mounting process described below.

In the mounting step, the light emitting diode 52 (resin-formed chip) is separated from the third temporary holding member 65 by a combination of mechanical means (element suction by vacuum suction) and laser ablation. FIG. 24 is a diagram showing that the light emitting diodes 52 arranged on the third temporary holding member 65 are picked up by the suction device 69. At this time, the suction holes 70 are opened in a matrix at the pixel pitch of the image display device, so that a large number of light emitting diodes 52 can be sucked together. The opening diameter at this time is, for example, about 100 μm in diameter, and the openings are formed in a matrix shape with a pitch of 600 μm, and about 300 pieces can be adsorbed at once. The member of the suction hole 70 at this time is, for example, Ni.
Those produced by electroforming or stainless steel (SU
A metal plate such as S) is used for etching, and a suction chamber 71 is formed in the back of the suction hole 70. By controlling the suction chamber 71 to a negative pressure, the light emitting diode 52 is sucked. Will be possible. The light emitting diode 52 is covered with the resin layer 62 at this stage, and the upper surface thereof is substantially flattened. Therefore, selective adsorption by the adsorption device 69 can be easily advanced.

The suction device 69 is provided with a device displacement preventing means so that the light emitting diode 52 (resin-formed chip) can be stably held at a fixed position when the device is sucked by vacuum suction. It is preferable to keep. Figure 2
5 is a suction device 69 provided with a device position shift prevention means 72.
FIG. In this example, the element position deviation prevention means 72 is formed as a positioning pin that abuts the peripheral surface of the resin-formed chip, and this is a peripheral surface of the resin-formed chip (specifically, the resin layer 62 cut by laser dicing). By contacting the cutting surface of the suction device 69.
And the resin-formed chip (that is, the light emitting diode 52) are accurately aligned with each other. The cut surface of the resin layer 62 cut by the laser dicing is not a perfect vertical surface but has a taper of about 5 ° to 10 °. Therefore, the positioning pin (element position deviation prevention means 7
If 2) also has the same taper, the suction device 6
Even if there is a slight displacement between 9 and the light emitting diode 52, it is promptly corrected.

At the time of peeling the light emitting diode 52, the element suction by the suction device 69 and the peeling of the resin-formed chip by UV light irradiation are combined so that the peeling proceeds smoothly. The peeling of the resin-formed chip is performed by irradiating UV light from the back surface side of the third temporary holding member 65. By this irradiation of UV light, peeling occurs at the interface between the photocatalyst layer 66 on the third temporary holding member 65 and the adhesive 67.

In FIG. 26, the light emitting diode 52 is arranged on the second substrate 7
FIG. 4 is a diagram showing the transfer to No. 3; Second substrate 73
Is a wiring board having a wiring layer 74, an adhesive layer 75 is previously applied to the second substrate 73 when the light emitting diode 52 is mounted, and the adhesive layer 75 on the lower surface of the light emitting diode 52 is cured, The light emitting diodes 52 can be fixedly arranged on the second substrate 73. At the time of this mounting, the suction chamber 71 of the suction device 69 is in a high pressure state, and the coupled state of the suction device 69 and the light emitting diode 52 by suction is released. The adhesive layer 75 can be composed of a UV curable adhesive, a thermosetting adhesive, a thermoplastic adhesive, or the like. The position where the light emitting diodes 52 are arranged on the second substrate 73 is farther from the arrangement on the temporary holding member 65. Energy for curing the resin of the adhesive layer 75 is supplied from the back surface of the second substrate 73. In the case of a UV curable adhesive, a UV irradiation device is used. In the case of a thermosetting adhesive, only the lower surface of the light emitting diode 52 is cured by infrared heating, and in the case of a thermoplastic adhesive, the adhesive is irradiated by infrared rays or laser. Are melted and bonded.

FIG. 27 is a diagram showing a process of arranging light emitting diodes 76 of another color on the second substrate 73. When the suction device 69 used in FIG. 24 or FIG. 25 is used as it is, and the mounting position on the second substrate 73 is simply shifted to the position of the color, the pixel pitch is fixed and the pixel composed of a plurality of colors is formed. Can be formed. Here, the light emitting diode 52 and the light emitting diode 76 do not necessarily have to have the same shape. In FIG. 27, the red light emitting diode 76 has a planar structure having no hexagonal pyramidal GaN layer, and the shape thereof is different from that of the other light emitting diodes 52.
Is already covered with the resin layer 62 and the adhesive 67 as a resin-formed chip, and the same handling is realized despite the difference in the element structure.

Next, as shown in FIG. 28, an insulating layer 77 is formed so as to cover the resin-formed chip including the light emitting diodes 52 and 76. As the insulating layer 77, a transparent epoxy adhesive, a UV curable adhesive, polyimide or the like can be used. After forming the insulating layer 77, a wiring forming step is performed. FIG. 29 is a diagram showing a wiring forming process.
Openings 78, 79, 80, 81, 82, 8 in the insulating layer 77
3 is a diagram in which wirings 84, 85 and 86 for connecting the anode / cathode electrode pads of the light emitting diodes 52 and 76 and the wiring layer 74 of the second substrate 73 are formed by forming No. 3 in FIG. The openings formed at this time, that is, via holes, can be made larger because the area of the electrode pads of the light emitting diodes 52 and 76 is made larger, and the positional accuracy of the via holes is rougher than that of via holes formed directly in each light emitting diode. Can be formed with. For example, the via hole at this time is about 6
A diameter of about 20 μm can be formed for a 0 μm square electrode pad. Further, the depth of the via hole has three kinds of depth, one for connecting to the wiring substrate, one for connecting to the anode electrode, and one for connecting to the cathode electrode. Therefore, it is controlled by the number of laser pulses to open the optimum depth. .

Then, as shown in FIG. 30, a protective layer 87 is formed.
And a black mask 88 is formed to complete the panel of the image display device. The protective layer 87 at this time is similar to the insulating layer 77 of FIG. 27, and a material such as a transparent epoxy adhesive can be used. The protective layer 87 is hardened by heating and completely covers the wiring. After this, the driver I
A drive panel will be manufactured by connecting C.

In the method for arranging the light emitting elements as described above, the distance between the elements is already increased at the time when the light emitting diodes 52 are held by the temporary holding members 59, 65, and the expanded spacing is utilized. Relatively sized electrode pad 6
4, 68 and the like can be provided. Since wiring is performed using the electrode pads 64 and 68 having a relatively large size, wiring can be easily formed even when the size of the final device is significantly larger than the element size. In addition, in the method of arranging the light emitting elements of this example, the electrode pads 64 and 68 can be accurately formed by flattening by covering the periphery of the light emitting diodes 52 with the cured resin layer 62, and the electrode pads 64 can be formed in a wider area than the elements. , 6
8 can be extended, and handling is facilitated when the transfer in the next second transfer step is advanced by the suction jig.

[0059]

As is apparent from the above description, according to the transfer method of the present invention, efficient transfer is possible, running cost can be suppressed, and a transfer method suitable for mass production is provided. It is possible to Further, according to the present invention, it is possible to improve the yield without damaging the element during transfer.

According to the element arraying method of the present invention,
It is possible to transfer the elements efficiently and reliably, and it is possible to smoothly perform the enlarged transfer for increasing the distance between the elements. Similarly, according to the method for manufacturing an image display device of the present invention, a light emitting element created by performing a fine processing by increasing the degree of integration, that is, the degree of integration, can be efficiently rearranged, Therefore, it is possible to manufacture a highly accurate image display device with high productivity.

[Brief description of drawings]

1A and 1B show an example of a transfer process using peeling by irradiation with UV light, in which FIG. 1A is a schematic diagram showing an arrangement state of elements on a transfer source substrate, and FIG. 1B is a stack of transfer destination substrates. FIG. 6 is a schematic diagram showing a combined state, FIG. 7C is a schematic diagram showing a UV light irradiation step, and FIG. 7D is a schematic diagram showing a state in which the transfer source substrate is removed.

FIG. 2 is a schematic diagram showing a method of arranging elements.

FIG. 3 is a schematic perspective view of a resin-formed chip.

FIG. 4 is a schematic plan view of a resin-formed chip.

5A and 5B are diagrams showing an example of a light emitting element, in which FIG. 5A is a sectional view and FIG. 5B is a plan view.

FIG. 6 is a schematic cross-sectional view showing a step of joining a first temporary holding member.

FIG. 7 is a schematic cross-sectional view showing a UV adhesive curing step.

FIG. 8 is a schematic sectional view showing a laser ablation step.

FIG. 9 is a schematic cross-sectional view showing a step of separating the first substrate.

FIG. 10 is a schematic cross-sectional view showing a Ga removing step.

FIG. 11 is a schematic cross-sectional view showing an element isolation groove forming step.

FIG. 12 is a schematic cross-sectional view showing a step of joining a second temporary holding member.

FIG. 13 is a schematic cross-sectional view showing a selective laser ablation and UV exposure process.

FIG. 14 is a schematic cross-sectional view showing a step of selectively separating light emitting diodes.

FIG. 15 is a schematic cross-sectional view showing a step of filling with resin.

FIG. 16 is a schematic cross-sectional view showing a resin layer thickness reduction step.

FIG. 17 is a schematic cross-sectional view showing a via forming step.

FIG. 18 is a schematic cross-sectional view showing a step of forming an anode-side electrode pad.

FIG. 19 is a schematic cross-sectional view showing a transfer process by irradiation with UV light.

FIG. 20 is a schematic cross-sectional view showing a step of separating a second temporary holding member.

FIG. 21 is a schematic cross-sectional view showing a contact semiconductor layer exposing step.

FIG. 22 is a schematic cross-sectional view showing the cathode-side electrode pad forming step.

FIG. 23 is a schematic sectional view showing a laser dicing process.

FIG. 24 is a schematic cross-sectional view showing a peeling process by irradiation with UV light and a selective pickup process by an adsorption device.

FIG. 25 is a schematic cross-sectional view showing an example of a suction device provided with element position shift prevention means.

FIG. 26 is a schematic cross-sectional view showing the step of transferring to the second substrate.

FIG. 27 is a schematic sectional view showing a step of transferring another light emitting diode.

FIG. 28 is a schematic cross-sectional view showing the insulating layer forming step.

FIG. 29 is a schematic sectional view showing a wiring forming step.

FIG. 30 is a schematic cross-sectional view showing a step of forming a protective layer and a black mask.

[Explanation of symbols]

1 transfer source substrate, 2 photocatalyst layer, 3 organic material layer, 4 elements, 5 transfer destination substrate, 6 adhesive layer, 52 light emitting diode, 59 second temporary holding member, 60 photocatalyst layer, peeling layer, 65 third Temporary holding member, 66 photocatalyst layer,
67 Adhesive

Claims (24)

[Claims] 1. A device transfer method for transferring devices arranged on a first substrate onto a second substrate, wherein devices are arranged on the first substrate via a photocatalyst layer and an organic material layer. Then, the device is transferred from the first substrate by irradiating with ultraviolet rays. 2. The device transfer method according to claim 1, wherein the first substrate is a transparent substrate that transmits the ultraviolet rays. 3. The method of transferring an element according to claim 1, wherein the photocatalyst layer contains titanium oxide as a material having a photocatalytic action. 4. The method for transferring an element according to claim 1, wherein the organic material layer contains polyimide as an organic material. 5. The method of transferring an element according to claim 1, wherein the ultraviolet lamp unit is used to irradiate the ultraviolet rays collectively. 6. The device transfer method according to claim 1, wherein an adhesive layer is formed on the second substrate. 7. The method of transferring an element according to claim 1, wherein the first substrate on which the photocatalytic layer is formed is repeatedly used. 8. An element arranging method for rearranging a plurality of elements arranged on a first substrate on a second substrate, wherein a state in which the elements are spaced apart from a state in which the elements are arranged on the first substrate. A first transfer step in which the element is transferred to hold the element on a temporary holding member, and the element held on the temporary holding member is further separated and transferred onto the second substrate. Two transfer steps, in at least one of the first transfer step and the second transfer step, the elements are arranged on the first substrate or the temporary holding member via the photocatalyst layer and the organic material layer, A method for arranging elements, wherein the elements are separated from the first substrate or the temporary holding member by irradiating with ultraviolet rays. 9. The first substrate or the temporary holding member,
9. The method for arranging elements according to claim 8, wherein the transparent substrate is a transparent substrate that transmits the ultraviolet rays. 10. The method for arranging elements according to claim 8, wherein the photocatalyst layer contains titanium oxide as a material having a photocatalytic action. 11. The method according to claim 8, wherein the organic material layer contains polyimide as an organic material. 12. The method of arranging elements according to claim 8, wherein ultraviolet rays are collectively emitted using an ultraviolet lamp unit. 13. The method for arranging elements according to claim 8, wherein an adhesive layer is formed on the temporary holding member or the second substrate. 14. The method for arranging elements according to claim 8, wherein the first substrate or the temporary holding member on which the photocatalytic layer is formed is repeatedly used. 15. The distance to be separated in the first transfer step is approximately an integer multiple of the pitch of the elements arranged on the first substrate, and the distance to be separated in the second transfer step is the first transfer. 9. The element arranging method according to claim 8, wherein the pitch is substantially an integral multiple of the pitch of the elements arranged on the temporary holding member in the step. 16. The device arraying method according to claim 8, wherein the device is a semiconductor device using a nitride semiconductor. 17. The element is a light emitting element, a liquid crystal control element,
9. The array of elements according to claim 8, which is an element selected from a photoelectric conversion element, a piezoelectric element, a thin film transistor element, a thin film diode element, a resistance element, a switching element, a micro magnetic element, a micro optical element, or a portion thereof. Method. 18. A method of manufacturing an image display device in which light-emitting elements are arranged in a matrix, wherein the light-emitting elements are transferred so that the light-emitting elements are spaced apart from the array of the light-emitting elements on the first substrate. And a second transfer step of transferring the light emitting element held by the temporary holding member to the second substrate while further separating the light emitting element held by the temporary holding member. In at least one of the first transfer step and the second transfer step, the light emitting elements are arranged on the first substrate or the temporary holding member through the photocatalyst layer and the organic material layer, and ultraviolet rays are irradiated. A method for manufacturing an image display device, characterized in that the light emitting element is peeled off from the first substrate or the temporary holding member by. 19. The method of manufacturing an image display device according to claim 18, wherein the light emitting element is embedded in a resin to form a chip component. 20. The method of manufacturing an image display device according to claim 18, wherein the light emitting element has a tip end portion having a tapered shape. 21. The method of manufacturing an image display device according to claim 20, wherein the tip portion has a conical shape or a polygonal pyramid shape. 22. The method of manufacturing an image display device according to claim 18, wherein the light emitting element is a semiconductor element. 23. The method of manufacturing an image display device according to claim 22, wherein the light emitting element is a semiconductor element using a nitride semiconductor. 24. The method of manufacturing an image display device according to claim 22, wherein the light emitting element is a semiconductor LED element.