JP4538951B2 - Element selective transfer method, image display device manufacturing method, and liquid crystal display device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an element selective transfer method for selectively transferring an element such as a semiconductor light emitting element onto a substrate, an image display device manufacturing method, and a liquid crystal display device manufacturing method.
[0002]
[Prior art]
Conventionally, when light emitting elements are arranged in a matrix and assembled into an image display device, the elements are formed on a substrate like a liquid crystal display (LCD) or a plasma display panel (PDP). Alternatively, a single LED package such as a light emitting diode display (LED display) is arranged. In conventional image display devices such as LCDs and PDPs, the element and pixel pitches and the manufacturing process thereof cannot be separated, so that each element is spaced by the pixel pitch of the image display device from the beginning of the manufacturing process. It is usually done. Further, for example, in the liquid crystal display device described in Japanese Patent Application Laid-Open No. 11-26733, the substrate used at the time of manufacturing the thin film device as the liquid crystal control element is different from the substrate used at the time of mounting the product, and is used at the time of mounting. A thin film device is transferred to a substrate.
[0003]
On the other hand, in the case of an LED display, the LED chip is taken out after dicing, and individually connected to an external electrode by wire bonding or flip chip bump connection to be packaged. In this case, the pixels are arranged at a pixel pitch as an image display device before or after packaging, but this pixel pitch is independent of the element pitch at the time of element formation.
[0004]
Since LEDs (light emitting diodes), which are light emitting elements, are expensive, an image display device using LEDs can be manufactured at low cost by manufacturing a large number of LED chips from a single wafer. That is, if an LED chip having a size of about 300 μm square is changed to an LED chip of several tens μm square and connected to manufacture an image display apparatus, the price of the image display apparatus can be reduced.
[0005]
Therefore, there is a technique for forming a relatively large display device such as an image display device by forming each device with a high degree of integration and moving each device to a wide area while being separated by transfer or the like, for example, Japanese Patent Laid-Open No. 56-17385. A manufacturing method of a display device using a light emitting diode described in the publication, a thin film transfer method described in US Pat. No. 5,438,241, a method of forming a display transistor array panel described in JP-A-11-142878, etc. The technology is known.
[0006]
In the method of manufacturing a display device using a light emitting diode described in Japanese Patent Application Laid-Open No. 56-17385, an LED wafer before dicing is attached to a first adhesive sheet, and dicing is performed on the sheet. The LED pellets thus obtained are collectively transferred to the second adhesive sheet. Of the diced LED pellets, a conductive paste is selectively applied only to the LED pellets to be transferred to the wiring board by a screen printing method. The LED pellets are bonded together with the second adhesive sheet in accordance with the positions of the electrodes on the substrate, and are selectively fixed and peeled off. LED pellets having different emission wavelengths of R, G, and B are sequentially selectively transferred.
[0007]
U.S. Pat. No. 5,438,241 discloses a transfer method in which elements formed densely on a substrate are roughly rearranged, and after transferring the elements to a stretchable substrate with an adhesive, the spacing and position of each element is changed. The stretchable substrate is stretched in the X and Y directions while monitoring. Then, each element on the stretched substrate is transferred onto a required display panel. In the technique described in JP-A-11-142878, the thin film transistor constituting the liquid crystal display portion on the first substrate is entirely transferred onto the second substrate, and then selectively from the second substrate. A technique for transferring to a third substrate corresponding to the pixel pitch is disclosed.
[0008]
[Problems to be solved by the invention]
However, the above-described technique causes the following problems. First, the technique described in Japanese Patent Laid-Open No. 56-17385 in which a conductive paste is selectively applied to the LED pellets by screen printing is effective for relatively large elements such as LED pellets. For a minute light emitting device having an element size of about 15 μm to 25 μm at a current level of about 100 μm or less, the screen printing position shift is large, and the application itself is very difficult.
[0009]
Further, in the transfer method in which a device formed densely on a substrate described in US Pat. No. 5,438,241 is roughly repositioned, the fixed point (fulcrum) at the time of expansion of the stretchable substrate is located on the bonding surface of the device chip. Depending on the situation, there is an essential problem that the device position is minimum and the chip size (≧ 20 μm) is shifted. Therefore, precise position control for each device chip is indispensable. Therefore, in order to form a high-definition TFT array panel that requires alignment accuracy of at least about 1 μm, it takes a lot of time for alignment including position measurement and control for each TFT device chip. Furthermore, in the case of transfer to a resin film having a large thermal expansion coefficient, the alignment accuracy is easily lost due to temperature / stress fluctuations before and after positioning. For these reasons, there is a very big problem in adopting it as a mass production technique.
[0010]
Further, in the technique described in JP-A-11-142878, UV light is selectively irradiated to a portion of a thin film transistor element to be transferred, and a UV release resin formed between the thin film transistor element and a transfer source substrate is used. The adhesive force is reduced. However, it takes time for the adhesive strength of the UV release resin to decrease due to the irradiation of ultraviolet rays, leading to a decrease in throughput in the process, and when the adhesive strength cannot be sufficiently reduced, the transfer yield also decreases. Will end up.
[0011]
Accordingly, the present invention provides a selective transfer method of elements, a method of manufacturing an image display apparatus, and the like so that the alignment accuracy is not impaired even after transfer and the transfer yield is not lowered when transferring a microfabricated element. It is another object of the present invention to provide a method for manufacturing a liquid crystal display device.
[0012]
[Means for Solving the Problems]
The element selective transfer method of the present invention is an element selective transfer method for selectively transferring a part of elements from a plurality of elements on a first substrate onto a second substrate. Light transmissive substrate Forming a plurality of elements on the first substrate; Thermoplastic resin layer Forming on the surface of the second substrate; By utilizing ablation by irradiation of an energy beam transmitted through the first substrate at the interface on the first substrate side of the element or at a peeling layer formed between the element and the first substrate, Selectively peeling a part of the plurality of elements from the first substrate; The peeled element enters the thermoplastic resin layer, Said Thermoplastic resin layer And selectively transferring the peeled element to the second substrate to selectively transfer the element to the second substrate.
[0013]
According to the above method, Thermoplastic resin layer Even if the element to be held has a very fine structure, Adhering the element to the thermoplastic resin layer The element can be reliably held, and thus the element is reliably transferred. Also, For example, By applying energy locally to the vicinity of the element by irradiation with a laser or the like, the processing can be performed in a relatively short time, and a decrease in yield can be prevented.
[0014]
In addition, other elements of the present invention Transfer method In In a selective transfer method of an element for selectively transferring a part of elements from a plurality of elements on a first substrate onto a second substrate, the light transmissive substrate Forming a plurality of elements each having a pointed head on the first substrate; Thermoplastic resin layer Forming on the surface of the second substrate; By utilizing ablation by irradiation of an energy beam transmitted through the first substrate at the interface on the first substrate side of the element or at a peeling layer formed between the element and the first substrate, Selectively peeling a part of the plurality of elements from the first substrate; The pointed head of the peeled element enters the thermoplastic resin layer, Said Thermoplastic resin layer And selectively transferring the peeled elements from the pointed head side to selectively transfer the elements to the second substrate.
[0015]
According to this selective transfer method, Thermoplastic resin layer Will hold the tip of the element, and the tip of the element itself will bite into the element holding layer and come into close contact, so that the element can be transferred reliably. In addition, by using the pointed head of the element, the area of the side of the pointed head is wider than when simply attaching a flat element. For thermoplastic resin layer Adhering to each other, reliable transfer is realized and the yield is improved.
[0016]
Further, in the method for manufacturing an image display device of the present invention, in the manufacturing method for manufacturing the image display device by selectively transferring some of the light emitting elements from the plurality of light emitting elements on the first substrate onto the second substrate. , Light transmissive substrate Forming a plurality of light emitting elements on the first substrate; Thermoplastic resin layer Forming on the surface of the second substrate; By utilizing ablation by irradiation of an energy beam transmitted through the first substrate at the interface on the first substrate side of the light emitting element, Selectively peeling a part of the plurality of light emitting elements from the first substrate; The peeled light emitting element enters the thermoplastic resin layer, Said Thermoplastic resin layer The step of selectively transferring the light emitting element to the second substrate by selectively holding the peeled light emitting element is repeated, and each pixel arranged in a matrix is provided with a light emitting element having a different emission wavelength. It is configured to be adjacent to each other.
[0017]
Furthermore, in the method for manufacturing a liquid crystal display device of the present invention, a liquid crystal display device for manufacturing a liquid crystal display device by selectively transferring some of the thin film transistor elements from the plurality of thin film transistor elements on the first substrate onto the second substrate. In the manufacturing method of Light transmissive substrate Forming a plurality of thin film transistor elements on the first substrate; Thermoplastic resin layer Forming on the surface of the second substrate; By utilizing ablation by irradiation of an energy beam transmitted through the first substrate in a release layer formed between the thin film transistor element and the first substrate, Selectively peeling a part of the plurality of thin film transistor elements from the first substrate; The peeled-off thin film transistor element enters the thermoplastic resin layer, Said Thermoplastic resin layer The step of selectively transferring the thin film transistor element to the second substrate by selectively holding the peeled thin film transistor element is performed on each pixel, and the thin film transistor element for controlling each pixel arranged in a matrix is provided for each pixel. It is characterized by forming each.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an enlargement transfer method in which elements are arranged apart from each other, which brings about advantages such as cost reduction when the element selective transfer method of the present invention is applied, will be described.
[0019]
[Example of selective transfer]
FIG. 1 is a diagram showing an example of enlarged transfer by selective transfer. In the selective transfer shown in FIG. 1, thinning transfer is performed in which a part of elements arranged in a matrix is thinned and transferred. Thinning transfer is performed by selectively transferring elements while facing the transfer source substrate and the transfer destination substrate (member). However, by making the transfer destination substrate (member) large, It is possible to move all of the elements on the substrate to the transfer destination substrate (member).
[0020]
FIG. 1 shows an example of an enlargement ratio of 3 in the first transfer process. When the first substrate 10 is used as a unit, the second substrate 11 has an area 9 times as large as the square of 3. For this reason, in order to transfer all of the elements 12 on the first substrate 10 which is the transfer source substrate, a total of nine transfers are performed. The elements 12 arranged in a matrix on the first substrate 10 are divided into 3 × 3 matrix units, and one of the elements 12 is sequentially transferred to the second substrate 11 and finally the entire element 12 is transferred. Is done.
[0021]
FIG. 1A schematically shows a state where the first element 12 is transferred to the second substrate 11 for every 3 × 3 matrix units among the elements 12 on the first substrate 10. (B) schematically shows the second element 12 being transferred to the second substrate 11 for each 3 × 3 matrix unit. In the second transfer, the alignment position of the first substrate 10 with respect to the second substrate 11 is shifted in the vertical direction in the figure, and the elements 12 can be arranged apart by repeating the same thinning transfer. FIG. 1C schematically shows that the eighth element 12 is transferred to the second substrate 11 every 3 × 3 matrix unit, and FIG. 1D shows every 3 × 3 matrix unit. 9 schematically shows the ninth element 12 being transferred to the second substrate 11. When the ninth element 12 is transferred for each 3 × 3 matrix unit, the first substrate 10 has no elements 12 and the second substrate 11 has a plurality of elements 12 separated in a matrix. Will be retained.
[0022]
[Light emitting element]
FIG. 2 shows a structure of a light-emitting element as an example of an element used in this embodiment. 2A is an element cross-sectional view, and FIG. 2B 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 that passes 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 made easy.
[0023]
First, with respect to the structure, a hexagonal pyramid-shaped GaN layer 32 selectively formed on an underlying growth layer 31 made of a GaN-based semiconductor layer is formed. Note that an insulating film (not shown) is present on the underlying growth layer 31, and the hexagonal pyramid-shaped GaN layer 32 is formed in the portion where the insulating film is opened by MOCVD or the like. The GaN layer 32 is a pyramidal growth layer covered with an S plane (1-101 plane) when the main surface of a sapphire substrate used during growth is a C plane, and is a region doped with silicon. is there. The inclined S-plane portion of the GaN layer 32 functions as a double heterostructure cladding. An InGaN layer 33, which is an active layer, is formed so as to cover the inclined S-plane of the GaN layer 32, and a magneto-doped GaN layer 34 is formed on the outside thereof. This magneto-doped GaN layer 34 also functions as a cladding.
[0024]
In such a light emitting diode, a p-electrode 35 and an n-electrode 36 are formed. The p-electrode 35 is formed by vapor-depositing a metal material such as Ni / Pt / Au or Ni (Pd) / Pt / Au formed on the magneto-doped GaN layer 34. The n-electrode 36 is formed by vapor-depositing a metal material such as Ti / Al / Pt / Au at the portion where the insulating film (not shown) is opened. When the n-electrode is taken out from the back side of the base growth layer 31, the formation of the n electrode 36 is not necessary on the surface side of the base growth layer 31.
[0025]
A GaN-based light emitting diode with such a structure is an element that can emit blue light, and can be peeled off from a sapphire substrate relatively easily by laser ablation, and is selected by selectively irradiating a laser beam. Exfoliation 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 pyramid structure in which a C surface is formed at the upper end. Further, other nitride-based light emitting elements, compound semiconductor elements, and the like may be used.
[0026]
[Selective transfer method of light emitting element, part 1]
Next, a method for selectively transferring a light emitting element will be described with reference to FIGS. As the light emitting element, a GaN-based light emitting diode as shown in FIG. 2 is used.
[0027]
First, as shown in FIG. 3A, a plurality of light emitting diodes 42 are formed in a matrix on the main surface of the first substrate 41. The size of the light emitting diode 42 may be several μm to about 100 μm, preferably about 10 μm to 30 μm. As shown in FIG. 2, the light emitting diode 42 has a substantially hexagonal pyramid pointed head 42 a formed of a pyramidal crystal growth layer. The light emitting diode 42 is made of a GaN-based material that is a nitride-based semiconductor layer. As the constituent material of the first substrate 41, a material having a high transmittance with respect to the wavelength of the laser light irradiated to the light emitting diode 42, such as a sapphire substrate, is used. The light emitting diode 42 is formed up to the p-electrode and the like, but the final wiring has not been made yet, and a groove for separating elements is formed so that the individual light emitting diodes 42 can be separated. This groove is formed by, for example, reactive ion etching. The first substrate 41 is opposed to the second substrate 43 at a distance that almost contacts the second substrate 43 to perform selective transfer.
[0028]
At the time of transfer, as shown in FIG. 3A, a thermoplastic resin layer 44 as an adhesive layer is formed in advance on the surface of the second substrate 43 facing the first substrate 41. Here, as an example of the second substrate 43, a glass substrate, a quartz glass substrate, a plastic substrate or the like can be used. Examples of the thermoplastic resin layer 44 on the second substrate 43 include, for example, polysulfone, aramid. , Polycarbonate, thermoplastic polyimide, etc., and ethylene-vinyl acetate copolymer, polyvinyl acetate, polyethylene, polypropylene, polyamide, etc. may be used or blended to improve adhesion, and In order to impart adhesiveness, rosin, modified rosin, adhesive polymer, terpene, modified terpene, hydrocarbons, chlorinated hydrocarbon, and the like may be prepared. Further, the film thickness of the thermoplastic resin layer 44 is set to the height of the pointed head 42a. The thermoplastic resin layer 44 may be uncured or may be cured conversely. However, when the pointed portion 42a of the light emitting diode 42 contacts, the pointed portion 42a is held by plastic deformation. It is preferable to have hardness.
[0029]
Subsequently, selective energy beam irradiation is performed to cause laser ablation to peel off the light emitting diode 42 from the first substrate 41. As the energy beam at this time, a laser beam 45 such as an excimer laser or a YAG laser is used. Because of the coherent characteristics of the laser beam 45, the laser beam 45 can be made to have a sufficiently narrow irradiation diameter, and can be selectively irradiated to the required back surface of the light emitting diode 42 by a required scan. The light emitting diode 42 at the selection target position is irradiated with laser light 45 from the back surface of the first substrate 41, and the light emitting diode 42 is peeled off from the first substrate 41 using laser ablation. The selection target position sequentially moves as shown in FIG. 1, and is expanded over the entire surface by repeating the required number of times. Since the GaN-based light emitting diode 42 is laser ablated at the interface with sapphire and decomposes into metallic Ga and nitrogen, it can be removed relatively easily. At this time, the irradiation diameter of the laser beam 45 is a diameter that completely irradiates the back surface of the light emitting diode 42 to be selected.
[0030]
By this peeling using laser ablation, the light emitting diode 42 for selective irradiation is separated at the interface between the GaN layer and the first substrate 41, and the surface of the opposite thermoplastic resin layer 44 as shown in FIG. Is transferred so as to pierce the pointed portion 42a of the light emitting diode 42, that is, the p-electrode portion. The light emitting diode 42 that has not been selectively irradiated with the laser remains on the first substrate 41 as it is, and is transferred at the subsequent selective transfer. In FIG. 3B, only the light emitting diodes 42 separated by two pitches are selectively transferred, but the thinning-out interval does not necessarily have to be two pitches. By such selective transfer, the light-emitting diodes 42 are arranged on the second substrate 43 so as to be separated from the case where they are arranged on the first substrate 41.
[0031]
Next, when the selective transfer of the light-emitting diodes 42 from the first substrate 41 to the second substrate 43 was performed, the thermoplastic resin layer 44 was further plastically deformed as shown in FIG. The light emitting diode 42 is sufficiently crimped. This pressure bonding is performed by pressing the pressure plate 46 from the thermoplastic resin layer 44 side of the second substrate 43. At the same time, the thermoplastic resin layer 44 is heated in order to soften the thermoplastic resin layer 44 and expand the contact area with the light emitting diode 42 having the pointed portion 42a. This heating temperature is set to be about the softening temperature of the thermoplastic resin layer 44. Heating of the thermoplastic resin layer 44 may be performed by disposing a heating means such as a pulse heat control device on the pressure plate 46, or may be performed by infrared irradiation that transmits through the second substrate 43. A release member 47 is formed on the surface of the pressure plate 46 to prevent a problem that the softened thermoplastic resin layer 44 and the pressure plate 46 adhere to each other. The release member 47 is a flat Teflon coating layer, and the pressure plate 46 can be made of a material such as molybdenum or titanium.
[0032]
When the pressure plate 46 is separated from the second substrate 43, each light emitting diode is separated together with the thermoplastic resin layer 44 on the surface of the release member 47 coated with Teflon, as shown in FIG. The pressed and heated thermoplastic resin layer 44 and the light emitting diode 42 constitute a substantially flat surface reflecting the surface of the flat release member 47. As described above, since the film thickness of the thermoplastic resin layer 44 is about the height of the pointed head 42 a, the molten thermoplastic resin layer 44 does not go around the pressure plate 46, and the light emitting diode 42 A flat back surface 42b appears. In the wiring process subsequent to the transfer process, wiring can also be formed on the flat back surface 42b on which the light emitting diode 42 appears, and the back surface 42b is flush with the surface of the pressurized and heated thermoplastic resin layer 44. For this reason, the wiring layer can be easily formed and patterned. The pressure plate 46 is released after the thermoplastic resin layer 44 is cooled and cured.
[0033]
In the element selective transfer method described above, the light emitting diodes 42 formed in the closest state are transferred onto the second substrate 43 while being separated by thinning. At this time, the thermoplastic resin layer 44 is pressed against the pointed portion 42a of the light emitting diode 42 by the plastic deformation, and is securely held. In addition, energy is locally applied to the vicinity of the element by irradiation with a laser, etc., and a heat treatment is performed in a relatively short time, so that the cost can be reduced and the holding position is accurate, so the yield is reduced. Can also be prevented. Further, the transfer of the light emitting diode 42 to the second substrate 43 can be relatively easily removed by utilizing the fact that the GaN-based material decomposes into metallic Ga and nitrogen at the interface with the sapphire.
[0034]
In the element transfer method described above, an example of a light emitting diode has been described. However, as an element used in the element transfer method of the present invention, other light emitting elements, liquid crystal control elements, photoelectric conversion elements, piezoelectric elements, An element selected from a thin film transistor element, a thin film diode element, a resistance element, a switching element, a minute magnetic element, and a minute optical element, or a portion thereof may be used.
[0035]
[Selective transfer method of light emitting element, 2]
In the selective transfer method of FIG. 3, the pressure plate 46 is used and the thermoplastic resin layer 44 is heated and pressurized. In this example, the laser is irradiated from the back surface of the second substrate without using the pressure plate. It is an example.
[0036]
First, as shown in FIG. 4A, a plurality of light emitting diodes 52 are formed in a matrix on the main surface of the first substrate 51. The size of the light emitting diode 52 can be several μm to about 100 μm, preferably about 10 μm to 30 μm. As shown in FIG. 2, the light-emitting diode 52 has a substantially hexagonal pyramidal pointed head 52a composed of a pyramidal crystal growth layer. The light emitting diode 52 is made of a GaN-based material that is a nitride-based semiconductor layer. As the constituent material of the first substrate 51, a material having a high transmittance with respect to the wavelength of the laser beam irradiated to the light emitting diode 52, such as a sapphire substrate, is used. The light emitting diode 52 is formed up to the p-electrode and the like, but the final wiring has not been made yet, and a groove for separating elements is formed, so that the individual light emitting diodes 52 can be separated. This groove is formed by, for example, reactive ion etching. The first substrate 51 is opposed to the second substrate 53 with a distance that is almost in contact with the second substrate 53, and selective transfer is performed.
[0037]
At the time of transfer, as shown in FIG. 4A, a thermoplastic resin layer 54 as an adhesive layer is formed in advance on the surface of the second substrate 53 facing the first substrate 51. Here, as an example of the second substrate 53, a light transmissive substrate such as a glass substrate, a quartz glass substrate, or a plastic substrate can be used. As an example of the thermoplastic resin layer 54 on the second substrate 53, for example, polysulfone (Polysulfone), aramid, polycarbonate, thermoplastic polyimide, etc. can be mentioned, and in order to improve adhesion, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyethylene, polypropylene, polyamide, etc. are used or blended. Furthermore, in order to impart adhesiveness, rosin, modified rosin, adhesive polymer, terpene, modified terpene, hydrocarbons, chlorinated hydrocarbon, and the like may be prepared. Further, the film thickness of the thermoplastic resin layer 54 is set to about the height of the pointed head 52a. When the thermoplastic resin layer 54 is formed on the second substrate 53, it is in a state of being completely cured. However, at the time of transfer, as shown in FIG. 4A, laser light 55 is irradiated to soften the region of the thermoplastic resin layer 54 corresponding to the element for selective transfer. That is, the laser light 55 is controlled to pass through the light-transmissive second substrate 53, and the thermoplastic resin layer 54 is selectively softened in the region irradiated with the laser light 55. The laser beam 55 is a laser beam applied to an infrared wavelength, for example, and the irradiated portion of the laser beam 55 is locally heated.
[0038]
When the thermoplastic resin layer 54 is selectively irradiated with the laser light 55 in this way, as shown in FIG. 4B, a selective energy beam is applied to a region corresponding to the region of the softened thermoplastic resin layer 54. The light emitting diode 52 is peeled off from the first substrate 51 by causing laser ablation. As the energy beam, a laser beam 57 such as an excimer laser or a YAG laser is used. The laser light 57 can have a sufficiently narrow irradiation diameter due to its coherent characteristics, and can selectively irradiate the back surface of the necessary light emitting diode 57 by a required scan. The light emitting diode 52 at the selection target position is irradiated from the back surface of the first substrate 51 with the laser light 57, and the light emitting diode 52 is peeled off from the first substrate 51 using laser ablation. The selection target position sequentially moves as shown in FIG. 1, and is expanded over the entire surface by repeating the required number of times. Since the GaN-based light emitting diode 52 causes laser ablation at the interface with sapphire and easily decomposes into metallic Ga and nitrogen, the light emitting diode 52 can be peeled off relatively easily. Note that the irradiation diameter of the laser light 57 at this time is a diameter that completely irradiates the back surface of the light emitting diode 52 according to the selection.
[0039]
Since the thermoplastic resin layer 54 has already been softened, the light emitting diode 52 peeled from the first substrate 51 is first brought into contact with the thermoplastic resin layer 54, and then the thermoplastic resin layer 54 is softened. The entire slope of the pointed head 52a adheres to the thermoplastic resin layer 54 as it is. Finally, as shown in FIG. 4C, the light emitting diode 52 is arranged so that the apex portion of the pointed head 52a of the light emitting diode 52 abuts on the second substrate 53 or goes to a little before that. Is held in the thermoplastic resin layer 54. By stopping the irradiation of the laser beam 55, the irradiated and softened thermoplastic resin layer 54 is cured, and as a result, the light emitting diode 52 is fixed to the second substrate 53 at a predetermined position.
[0040]
In the element selective transfer method described above, the light-emitting diodes 52 formed in the close-packed state are transferred onto the second substrate 53 while being spaced apart by thinning. At this time, the thermoplastic resin layer 54 is pressed against the tip 52a of the light-emitting diode 52 by the plastic deformation, and is securely held. In addition, energy is locally applied to the vicinity of the element by irradiation with a laser or the like, and heat treatment is performed in a relatively short time, so that the cost can be reduced and the position where the light emitting diode 52 is held is also accurate. Therefore, it is possible to prevent a decrease in yield. In addition, the transfer of the light emitting diode 52 formed of a GaN-based material to the second substrate 53 is relatively simple using laser ablation in which the GaN-based material decomposes into metallic Ga and nitrogen at the interface with the sapphire. Can be peeled off.
[0041]
[Selective transfer method of light emitting element, part 3]
This example is a modification of the selective transfer method of the light emitting element shown in FIG. 4, and as shown in FIG. 5, the spot of the laser beam that is transmitted through the second substrate is reduced and the n electrode of the light emitting diode is applied. This is an example in which the side can be held outside the thermoplastic resin.
[0042]
First, as shown in FIG. 5A, a plurality of light emitting diodes 62 are formed in a matrix on the main surface of the first substrate 61. Similar to the selective transfer method of the light emitting element described above, the size of the light emitting diode 62 can be several μm to about 100 μm, preferably about 10 μm to 30 μm. As shown in FIG. 2, the light emitting diode 62 has a substantially hexagonal pyramid-shaped pointed head 62a formed of a pyramidal crystal growth layer. The light emitting diode 62 is made of a GaN-based material that is a nitride-based semiconductor layer. As the constituent material of the first substrate 61, a material having a high transmittance at the wavelength of the laser light irradiated to the light emitting diode 62, such as a sapphire substrate, is used. The light emitting diode 62 is formed up to the p-electrode and the like, but the final wiring has not been made yet, and a groove for separating elements is formed, so that the individual light emitting diodes 62 can be separated. This groove is formed by, for example, reactive ion etching. Such a first substrate 61 is opposed to the second substrate 63 at a distance that almost contacts the second substrate 63 to perform selective transfer.
[0043]
At the time of transfer, as shown in FIG. 5A, a thermoplastic resin layer 64 as an adhesive layer is formed in advance on the surface of the second substrate 63 facing the first substrate 61. Here, as an example of the second substrate 63, a light transmissive substrate such as a glass substrate, a quartz glass substrate, or a plastic substrate can be used. As an example of the thermoplastic resin layer 64 on the second substrate 63, for example, polysulfone (Polysulfone), aramid, polycarbonate, thermoplastic polyimide, etc. can be mentioned, and in order to improve adhesion, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyethylene, polypropylene, polyamide, etc. are used or blended. Furthermore, in order to impart adhesiveness, rosin, modified rosin, adhesive polymer, terpene, modified terpene, hydrocarbons, chlorinated hydrocarbon, and the like may be prepared. The thermoplastic resin layer 64 is in a fully cured state when it is formed on the second substrate 63, but during the transfer, as shown in FIG. 5A, the laser beam 65 is applied to the selective transfer. Irradiation is performed to soften the region of the thermoplastic resin layer 64 corresponding to the element. That is, the laser beam 65 is controlled to pass through the light-transmitting second substrate 63, and the thermoplastic resin layer 64 is selectively softened in the region irradiated with the laser beam 65. The laser beam 65 is a laser beam applied to an infrared wavelength, for example, and the irradiated portion of the laser beam 65 is locally heated. In particular, in this example, the spot diameter irradiated with the laser light 65 is smaller than the base end portion of the substantially hexagonal pyramidal pointed portion 62 a of the light emitting diode 62. For this reason, the softened region 64y of the thermoplastic resin layer 64 has a smaller diameter than the base end portion of the pointed head 62a, and the periphery thereof is kept cured.
[0044]
Thus, when the thermoplastic resin layer 64 is selectively irradiated with the laser beam 65 with a small beam diameter, as shown in FIG. 5B, it corresponds to the region 64y of the softened thermoplastic resin layer 64. The region is irradiated with a selective energy beam to cause laser ablation to peel off the light emitting diode 62 from the first substrate 61. This laser ablation is the same as the process shown in FIGS. That is, since the GaN-based light emitting diode 62 causes laser ablation at the interface with sapphire and easily decomposes into metallic Ga and nitrogen, the light emitting diode 62 can be peeled off relatively easily. Note that the irradiation diameter of the laser light 67 at this time is a diameter that completely irradiates the back surface of the light emitting diode 62 to be selected.
[0045]
Since the thermoplastic resin layer 64 has already been softened, the light emitting diode 62 peeled off from the first substrate 61 first comes into contact with the thermoplastic resin layer 64, and then the thermoplastic resin layer 64 softens. The inclined surface of the pointed head 62a adheres to the thermoplastic resin layer 64 as it is. Here, in this example, since the softened region 64y of the thermoplastic resin layer 64 has a diameter smaller than the base end portion of the pointed head 62a, the middle of the inclined surface of the pointed head 62a is the middle of the thermoplastic resin layer 64. It stops at the hardened portion around the small-diameter region 64y. Therefore, as shown in FIG. 5C, the portion of the base growth layer of the light-emitting diode 62 is placed outside the thermoplastic resin layer 64, and the light-emitting diode 62 Is held by the thermoplastic resin layer 64. Thus, since the back surface 62b of the light emitting diode 62 is securely held without being buried in the thermoplastic resin layer 64, wiring to the n-electrode in the subsequent process is a technically easy process.
[0046]
In the element selective transfer method described above, the light emitting diodes 62 formed in the closest state are transferred onto the second substrate 63 while being separated by thinning. At this time, the thermoplastic resin layer 64 is pressed against the pointed portion 62a of the light emitting diode 62 by the plastic deformation and is securely held. In addition, energy is locally applied to the vicinity of the element by irradiation with a laser or the like, and heat treatment is performed in a relatively short time, so that the cost can be reduced and the position where the light emitting diode 62 is held is also accurate. Therefore, it is possible to prevent a decrease in yield. In addition, the transfer of the light-emitting diode 62 formed of a GaN-based material to the second substrate 63 is relatively easy using laser ablation in which the GaN-based material decomposes into metallic Ga and nitrogen at the interface with the sapphire. Can be peeled off. Further, by reducing the irradiation diameter of the laser light 65, the back surface 62b of the light emitting diode 62 is securely held without being buried in the thermoplastic resin layer 64, and therefore wiring and the like can be easily advanced.
[0047]
[Method for Manufacturing Image Display Device]
By repeating the selective transfer of the elements as described above, it becomes possible to accurately arrange the elements over the entire screen of the image display apparatus. In other words, by repeating selective transfer of elements as described above, each pixel arranged in a matrix can be made to have a structure in which light emitting elements having different emission wavelengths are adjacent to each other. Thus, an image display device capable of reducing the cost can be manufactured.
[0048]
FIG. 6 is a process diagram showing a structure close to the final image display device, and is a cross section of the device where a wiring layer is formed. The RGB light emitting diodes 79, 81, and 82 are transferred one step further from the above-described second substrates 43, 53, and 63, arranged on the third substrate 80, and coated with an insulating layer 74. The place where wiring was given later is shown. The red light emitting diode 81 does not have a hexagonal pyramid GaN layer, and is different in shape from the other blue light emitting diodes 79 and green light emitting diodes 82. Openings 85, 86, 87, 88, 89, 90 are formed in the insulating layer 74, and the anode and cathode electrode pads of the light emitting diodes 79, 81, 82 are connected to the wiring electrode layer 77 of the third substrate 80. The wiring 83, 84, 91 is formed.
[0049]
The opening formed at this time, that is, the via hole, increases the area of the electrode pads 76, 75 of the light emitting diodes 79, 81, 82, so that the via hole shape is large, and the positional accuracy of the via hole is also the via hole directly formed in each light emitting diode. It can be formed with coarser accuracy. At this time, a via hole having a diameter of about 20 μm can be formed for the electrode pads 76 and 75 of about 60 μm square. A black chrome layer 78 is formed below the electrode layer 77 and functions as a shadow mask. In addition, there are three types of depth of via holes, one connecting to the wiring board, one connecting to the anode electrode, and one connecting to the cathode electrode, so the optimum depth is controlled by controlling the number of laser pulses. . Thereafter, a protective layer is formed on the wiring, and the panel of the image display device is completed. Thereafter, a driver IC is connected from the wiring at the end of the panel to produce a drive panel, thereby completing the image display device.
[0050]
[Selective Transfer Method of Thin Film Transistor Element, Part 1]
Next, a selective transfer method of the thin film transistor element will be described with reference to FIGS. The thin film transistor element can be used as a liquid crystal display device by being arranged on a substrate by selective transfer.
[0051]
First, as shown in FIG. 7A, a plurality of thin film transistor elements 102 are formed in a matrix on the main surface of the first substrate 101. The thin film transistor element 102 is a field effect transistor having an SOI structure and having a channel region formed in a thin film silicon layer made of polycrystalline silicon or recrystallized silicon. As a constituent material of the first substrate 101, a material having a high transmittance at the wavelength of the laser beam irradiated on the thin film transistor element 102, such as a glass substrate, is used. The thin film transistor element 102 has not yet been finally wired, and has a groove for separating elements, so that the individual thin film transistor elements 102 can be separated. This groove is formed by, for example, reactive ion etching. Such a first substrate 101 is opposed to the second substrate 103 at a distance that almost contacts the second substrate 103, and selective transfer is performed. Note that a release film such as an amorphous silicon film or a nitride film that is ablated by laser irradiation is formed on the main surface side of the first substrate 101 of each thin film transistor element 102.
[0052]
At the time of transfer, as shown in FIG. 7A, a thermoplastic resin layer 104 as an adhesive layer is formed in advance on the surface of the second substrate 103 facing the first substrate 101. Here, as an example of the second substrate 103, a glass substrate, a quartz glass substrate, a plastic substrate, or the like can be used. Examples of the thermoplastic resin layer 104 on the second substrate 103 include, for example, polysulfone, aramid, and the like. , Polycarbonate, thermoplastic polyimide, etc., and ethylene-vinyl acetate copolymer, polyvinyl acetate, polyethylene, polypropylene, polyamide, etc. may be used or blended to improve adhesion, and In order to impart adhesiveness, rosin, modified rosin, adhesive polymer, terpene, modified terpene, hydrocarbons, chlorinated hydrocarbon, and the like may be prepared. The thermoplastic resin layer 104 may be uncured or may be cured conversely. However, when the surface portion of the thin film transistor element 102 comes into contact with the thermoplastic resin layer 104, the thermoplastic resin layer 104 is hard enough to hold the surface portion by plastic deformation. It is preferable to have.
[0053]
Subsequently, selective energy beam irradiation is performed to cause laser ablation of the above-described peeling film, and the thin film transistor element 102 is peeled from the first substrate 101. As the energy beam at this time, a laser beam 105 such as an excimer laser or a YAG laser is used. Because of the coherent characteristics of the laser beam 105, the irradiation diameter can be sufficiently reduced, and the necessary back surface of the thin film transistor element 102 can be selectively irradiated by a required scan. The thin film transistor element 102 at the selection target position is irradiated from the back surface of the first substrate 101 with a laser beam 105, and the thin film transistor element 102 is peeled off from the first substrate 101 using laser ablation. The selection target position sequentially moves as shown in FIG. 1, and is expanded over the entire surface by repeating the required number of times. In this example, the thin film transistor element 102 can be peeled relatively easily because laser ablation occurs due to the peeling film at the interface with the first substrate 101. Note that the irradiation diameter of the laser beam 105 at this time is a diameter that completely irradiates the back surface of the thin film transistor element 102 to be selected.
[0054]
The thin film transistor element 102 subjected to selective irradiation is separated at the interface between the back surface and the first substrate 101 by peeling using this laser ablation, and the surface of the thermoplastic resin layer 104 on the opposite side as shown in FIG. The surface of the thin film transistor element 102 is transferred so as to be partially buried. The thin film transistor element 102 that has not been subjected to selective laser irradiation remains on the first substrate 101 as it is, and is transferred at the subsequent selective transfer. In FIG. 7B, only the thin film transistor elements 102 separated by two pitches are selectively transferred, but the thinning interval is not necessarily two pitches. According to such selective transfer, the thin film transistor elements 102 are arranged on the second substrate 103 at a distance from the arrangement on the first substrate 101.
[0055]
Next, when the selective transfer of the thin film transistor element 102 from the first substrate 101 to the second substrate 103 was performed, the thermoplastic resin layer 104 was further plastically deformed as shown in FIG. The thin film transistor element 102 is sufficiently pressed. This pressure bonding is performed by pressing the pressure plate 106 from the thermoplastic resin layer 104 side of the second substrate 103. At the same time, the thermoplastic resin layer 104 is heated to soften the thermoplastic resin layer 104 and increase the contact area with the thin film transistor element 102. This heating temperature is set to be about the softening temperature of the thermoplastic resin layer 104. Heating of the thermoplastic resin layer 104 may be performed by disposing a heating means such as a pulse heat control device on the pressure plate 106, or by infrared irradiation that transmits through the second substrate 103. A release member 107 is formed on the surface of the pressure plate 106 to prevent a problem that the softened thermoplastic resin layer 104 and the pressure plate 106 adhere to each other. The release member 107 is a flat Teflon coating layer, and the pressure plate 106 can be made of a material such as molybdenum or titanium.
[0056]
When the pressure plate 106 is separated from the second substrate 103, each thin film transistor element is separated together with the thermoplastic resin layer 104 on the surface of the release member 107 coated with Teflon, as shown in FIG. The pressed and heated thermoplastic resin layer 104 and the thin film transistor element 102 constitute a substantially flat surface reflecting the surface of the flat release member 107. As described above, since the film thickness of the thermoplastic resin layer 104 is about the height of the element, the molten thermoplastic resin layer 104 does not wrap around the pressure plate 106 side, and the flat back surface of the thin film transistor element 102 102b appears. In the wiring process subsequent to the transfer process, wiring can be formed on the flat back surface 102b on which the thin film transistor element 102 appears. The back surface 102b is flush with the surface of the pressurized and heated thermoplastic resin layer 104. For this reason, the wiring layer can be easily formed and patterned. The pressure plate 106 is released after the thermoplastic resin layer 104 is cooled and cured.
[0057]
In the element selective transfer method described above, the thin film transistor elements 102 formed in the close-packed state are transferred onto the second substrate 103 while being spaced apart by thinning. At this time, the thermoplastic resin layer 104 is pressed against the surface portion of the thin film transistor element 102 by the plastic deformation and is securely held. In addition, energy is locally applied to the vicinity of the element by irradiation with a laser, etc., and a heat treatment is performed in a relatively short time, so that the cost can be reduced and the holding position is accurate, so the yield is reduced. Can also be prevented. Further, the transfer of the thin film transistor element 102 to the second substrate 103 can be relatively easily peeled off using laser ablation.
[0058]
In the element transfer method described above, the example of the thin film transistor element has been described. However, as the element used in the element transfer method of the present invention, other liquid crystal control elements, light emitting elements, photoelectric conversion elements, piezoelectric elements It may be an element selected from a thin film transistor element, a thin film diode element, a resistance element, a switching element, a minute magnetic element, and a minute optical element, or a portion thereof.
[0059]
[Selective transfer method of thin film transistor element, 2]
In the selective transfer method shown in FIG. 7, the pressure plate 106 is used and the thermoplastic resin layer 104 is heated and pressed. In this example, the laser is irradiated from the back surface of the second substrate without using the pressure plate. It is an example.
[0060]
First, as shown in FIG. 8A, on the main surface of the first substrate 111, a plurality of thin film transistor elements 112 are formed in a matrix. The thin film transistor element 112 is a field effect transistor having an SOI structure and having a channel region formed in a thin film silicon layer made of polycrystalline silicon or recrystallized silicon. As a constituent material of the first substrate 111, a material having a high transmittance with respect to the wavelength of the laser beam irradiated on the thin film transistor element 112, such as a glass substrate, is used. The thin film transistor element 112 has not been finally wired yet, and a groove for separating elements is formed, so that the individual thin film transistor elements 112 can be separated. This groove is formed by, for example, reactive ion etching. Such a first substrate 111 is opposed to the second substrate 113 with a distance that is almost in contact with it, and selective transfer is performed. Note that a release film such as an amorphous silicon film or a nitride film that is ablated by laser irradiation is formed on the main surface side of the first substrate 111 of each thin film transistor element 112.
[0061]
At the time of transfer, as shown in FIG. 8A, a thermoplastic resin layer 114 as an adhesive layer is formed in advance on the surface of the second substrate 113 facing the first substrate 111. Here, as an example of the second substrate 113, the same material as that of the second substrate 103 can be used. When the thermoplastic resin layer 114 is formed on the second substrate 113, it is in a state of being completely cured. However, at the time of transfer, as shown in FIG. 8A, a laser beam 115 is irradiated to soften the region of the thermoplastic resin layer 114 corresponding to the element for selective transfer. That is, the laser beam 115 is controlled to pass through the light-transmissive second substrate 113, and the thermoplastic resin layer 114 is selectively softened in the region irradiated with the laser beam 115. This laser beam 115 is a laser beam applied to, for example, an infrared wavelength, and the irradiated portion of the laser beam 115 is locally heated.
[0062]
When the thermoplastic resin layer 114 is selectively irradiated with the laser beam 115 in this manner, as shown in FIG. 8B, a selective energy beam is applied to a region corresponding to the softened thermoplastic resin layer 114 region. The thin film transistor element 112 is peeled from the first substrate 111 by causing laser ablation. As the energy beam, laser light 117 such as an excimer laser or a YAG laser is used. The laser beam 117 can have a sufficiently narrow irradiation diameter because of its coherent characteristics, and can selectively irradiate the back surface of the necessary thin film transistor element 117 by a required scan. The thin film transistor element 112 at the selection target position is irradiated from the back surface of the first substrate 111 with a laser beam 117, and the thin film transistor element 112 is peeled off from the first substrate 111 using laser ablation. The selection target position sequentially moves as shown in FIG. 1, and is expanded over the entire surface by repeating the required number of times. The thin film transistor element 112 causes laser ablation at the interface, and the thin film transistor element 112 can be peeled off relatively easily. Note that the irradiation diameter of the laser beam 117 at this time is a diameter that completely irradiates the back surface of the thin film transistor element 112 to be selected.
[0063]
Since the thermoplastic resin layer 114 has already been softened, the surface portion of the thin film transistor element 112 peeled from the first substrate 111 is first brought into contact with the thermoplastic resin layer 114, and then the thermoplastic resin layer 114 is softened. The side part adheres to the thermoplastic resin layer 114 as it is. Finally, as shown in FIG. 8C, the thin film transistor element 112 is held by the thermoplastic resin layer 114 so that the thin film transistor element 112 is in contact with the second substrate 113 or just before it. Is done. By stopping the irradiation of the laser beam 115, the thermoplastic resin layer 114 softened by the irradiation is cured, and as a result, the thin film transistor element 112 is fixed to the second substrate 113 at a predetermined position.
[0064]
In the element selective transfer method described above, the thin film transistor elements 112 formed in the closest state are transferred onto the second substrate 113 while being spaced apart by thinning. At this time, the thermoplastic resin layer 114 is pressed against the surface of the thin film transistor element 112 by the plastic deformation and is securely held. In addition, energy is locally applied to the vicinity of the element by irradiation with a laser or the like, and heat treatment is performed in a relatively short time, so that the cost can be reduced and the position where the thin film transistor element 112 is held is also accurate. Therefore, it is possible to prevent a decrease in yield. In addition, the transfer of the thin film transistor element 112 to the second substrate 113 can be relatively easily removed using laser ablation.
[0065]
[Selective Transfer Method of Thin Film Transistor Element, Part 3]
This example is a modification of the selective transfer method of the thin film transistor element shown in FIG. 8, and as shown in FIG. 9, the spot of the laser beam irradiated through the second substrate is reduced, and the elasticity of the resin layer This is an example in which a thin film transistor element is gripped.
[0066]
First, as shown in FIG. 9A, on the main surface of the first substrate 121, a plurality of thin film transistor elements 122 are formed in a matrix. The thin film transistor element 122 is a field effect transistor having an SOI structure and having a channel region formed in a thin film silicon layer made of polycrystalline silicon or recrystallized silicon. As a constituent material of the first substrate 121, a material having a high transmittance with respect to the wavelength of the laser beam irradiated on the thin film transistor element 122, such as a glass substrate, is used. The thin film transistor element 122 has not yet been finally wired, and a groove for separating elements is formed, so that the individual thin film transistor elements 122 can be separated. This groove is formed by, for example, reactive ion etching. Such a first substrate 121 is opposed to the second substrate 123 with a distance that almost contacts the second substrate 123 to perform selective transfer. Note that a release film such as an amorphous silicon film or a nitride film that is ablated by laser irradiation is formed on the main surface side of the first substrate 121 of each thin film transistor element 122.
[0067]
At the time of transfer, as shown in FIG. 9A, a thermoplastic resin layer 124 as an adhesive layer is formed in advance on the surface of the second substrate 123 facing the first substrate 121. Here, as an example of the second substrate 123, a light transmissive substrate such as a glass substrate, a quartz glass substrate, or a plastic substrate can be used. As an example of the thermoplastic resin layer 124 on the second substrate 123, for example, polysulfone (Polysulfone), aramid, polycarbonate, thermoplastic polyimide, etc. can be mentioned, and in order to improve adhesion, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyethylene, polypropylene, polyamide, etc. are used or blended. Furthermore, in order to impart adhesiveness, rosin, modified rosin, adhesive polymer, terpene, modified terpene, hydrocarbons, chlorinated hydrocarbon, and the like may be prepared. The thermoplastic resin layer 124 is in a fully cured state in the state where it is formed on the second substrate 123, but at the time of transfer, as shown in FIG. Irradiation is performed to soften the region of the thermoplastic resin layer 124 corresponding to the element. That is, the laser beam 125 is controlled to pass through the light-transmitting second substrate 123, and the thermoplastic resin layer 124 is selectively softened in the region irradiated with the laser beam 125. This laser beam 125 is a laser beam applied to an infrared wavelength, for example, and the irradiated portion of the laser beam 125 is locally heated. In particular, in this example, the spot diameter irradiated with the laser beam 125 is smaller than the element size of the thin film transistor element 122. For this reason, the softened region 124y of the thermoplastic resin layer 124 has a diameter smaller than the element size of the thin film transistor element 122, and the periphery thereof is kept cured.
[0068]
Thus, when the thermoplastic resin layer 124 is selectively irradiated with the laser beam 125 with a small beam diameter, as shown in FIG. 9B, it corresponds to the region 124y of the softened thermoplastic resin layer 124. The region is irradiated with a selective energy beam to cause laser ablation to peel off the thin film transistor element 122 from the first substrate 121. This laser ablation is the same as the process shown in FIGS. That is, the thin film transistor element 122 causes laser ablation at the interface with the first substrate 121 and can be peeled off relatively easily. Note that the irradiation diameter of the laser beam 127 at this time is a diameter that completely irradiates the back surface of the thin film transistor element 122 to be selected.
[0069]
Since the thermoplastic resin layer 124 has already been softened, the surface of the thin film transistor element 122 peeled from the first substrate 121 is first brought into contact with the thermoplastic resin layer 124, and then the thermoplastic resin layer 124 is softened. The thermoplastic resin layer 124 is bonded as it is. Here, in this example, since the softened region 124y of the thermoplastic resin layer 124 has a diameter smaller than the element size of the thin film transistor element 122, the side surface of the thin film transistor element 122 is the small diameter region 124y of the thermoplastic resin layer 124. As shown in FIG. 9C, the insulating region portion of the thin film transistor element 122 is placed outside the thermoplastic resin layer 124, and the thin film transistor element 122 itself becomes the thermoplastic resin layer 124. Will be held. Thus, since the back surface 122b of the thin film transistor element 122 is securely held without being buried in the thermoplastic resin layer 124, the wiring in the subsequent process is a technically easy process.
[0070]
In the selective transfer method of thin film transistor elements described above, the thin film transistor elements 122 formed in the closest state are transferred onto the second substrate 123 while being separated by thinning. At this time, the thermoplastic resin layer 124 is pressed against the surface portion of the thin film transistor element 122 by the plastic deformation, and is securely held. In addition, energy is locally given to the vicinity of the element by irradiation with a laser or the like, and heat treatment is performed in a relatively short time, so that cost can be reduced and the position where the thin film transistor element 122 is held is also accurate. Therefore, it is possible to prevent a decrease in yield. Further, the transfer of the thin film transistor element 122 to the second substrate 123 can be relatively easily peeled off using laser ablation. Further, by reducing the irradiation diameter of the laser beam 125, the back surface 122b of the thin film transistor element 122 is securely held without being buried in the thermoplastic resin layer 124, so that wiring and the like can be easily advanced.
[0071]
[Example of manufacturing method of liquid crystal display device]
By repeating the selective transfer of the elements as described above, the elements can be precisely arranged over the entire screen of the liquid crystal display device. That is, by repeating the selective transfer of the thin film transistor elements as described above, it is possible to make each pixel arranged in a matrix form a thin film transistor element for each pixel, and to perform high-resolution and selective transfer of enlargement. A liquid crystal display device that can be used for cost reduction can be manufactured.
[0072]
FIG. 10 is a process diagram showing a structure close to the final liquid crystal display device, and is a cross section of the device where a wiring layer is formed. After each thin film transistor element 132 is transferred onto the second substrate 138 in accordance with the pixel pitch, an interlayer insulating film 140 is formed on each thin film transistor element 132 as shown in FIG. After forming the part and the wiring part, a pixel electrode 141 made of transparent ITO or the like is formed for each pixel, and an alignment film 142 is formed thereon. In parallel with this, a common electrode 145 made of an ITO film or the like is formed on the transparent counter substrate 146, and an alignment film 144 is formed thereon. Finally, the second substrate 138 and the transparent counter substrate 146 are opposed to each other with a required gap, and the liquid crystal 143 is injected between the second substrate 138 and the transparent counter substrate 146 to complete the liquid crystal display device. Accordingly, it is possible to manufacture a liquid crystal display device capable of drastically reducing costs by using enlarged selective transfer in which thin film transistor elements that are initially manufactured at a high density are arranged apart from each other on the final substrate. In this embodiment, the element transferred in the liquid crystal display device is a thin film transistor element. However, the transferred element and the part of the element are other transistor elements for driving, other part of the electrode, pixel electrode, and the like. It may be an element or a part of an element.
[0073]
【The invention's effect】
According to the element selective transfer method and the image display device manufacturing method of the present invention described above, the element formed in the close-packed state is transferred separately on the second substrate, so that an image as a final product is obtained. The manufacturing cost of the display device can be reduced, and the thermoplastic resin layer is pressed against the tip of the light-emitting diode by the plastic deformation, and the element can be reliably held. Therefore, since the position where the element is held in the selective transfer is accurately held, the yield can be improved.
[0074]
In addition, energy is locally given to the vicinity of the element by irradiation with a laser or the like, and heat treatment is performed in a relatively short time, so that cost can be reduced. In addition, for the transfer of light-emitting diodes made of GaN-based materials to the second substrate, laser ablation in which the GaN-based material decomposes into metallic Ga and nitrogen at the interface with sapphire is used for relatively easy peeling. Is realized, which can contribute to further reduction in the manufacturing cost of the image display device. Furthermore, it is possible to control the n-electrode side so as not to be buried in the thermoplastic resin layer by adjusting the irradiation diameter of the laser beam.
[0075]
According to the element selective transfer method and the image display apparatus manufacturing method of the present invention described above, the thin film transistor element used in the liquid crystal display device is transferred onto the second substrate as the element formed in the closest state. As a result, the manufacturing cost of the image display device as the final product can be reduced. Further, since the position where the thin film transistor element is held at the time of selective transfer is accurately held, the yield can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a selective transfer method of elements by thinning transfer according to the present invention.
FIGS. 2A and 2B are diagrams showing an example of a light emitting element used in the element selective transfer method according to the embodiment of the present invention, and FIG.
FIGS. 3A and 3B are process cross-sectional views illustrating a light-emitting element selective transfer method (No. 1) according to an embodiment of the present invention, wherein FIG. 3A is a laser light irradiation process, and FIG. (C) shows a pressurizing and heating process using a pressure plate, and (d) shows a separation process of the pressurizing plate.
FIGS. 4A and 4B are process cross-sectional views illustrating a selective transfer method (part 2) of a light emitting element according to an embodiment of the present invention, wherein FIG. 4A is a process of softening a thermoplastic resin layer, and FIG. The light emitting diode peeling step, (c) shows the step of holding the light emitting diode by the thermoplastic resin layer.
FIGS. 5A and 5B are process cross-sectional views illustrating a light-emitting element selective transfer method (part 3) according to an embodiment of the present invention, wherein FIG. Denotes a step of peeling a light emitting diode by laser light irradiation, and (c) denotes a step of holding the light emitting diode by a thermoplastic resin layer.
FIG. 6 is a process cross-sectional view illustrating a wiring formation process in the method for manufacturing an image display device according to the embodiment of the present invention.
7A and 7B are process cross-sectional views illustrating a selective transfer method (No. 1) of a thin film transistor element according to an embodiment of the present invention, wherein FIG. 7A is a laser light irradiation process, and FIG. (C) shows a pressurizing and heating process using a pressure plate, and (d) shows a separation process of the pressurizing plate.
FIGS. 8A and 8B are process cross-sectional views illustrating a selective transfer method (part 2) of a thin film transistor element according to an embodiment of the present invention, wherein FIG. 8A is a process of softening a thermoplastic resin layer, and FIG. The thin film transistor element peeling step, (c) shows the thin film transistor element holding step by the thermoplastic resin layer.
FIGS. 9A and 9B are process cross-sectional views illustrating a thin film transistor element selective transfer method (part 3) according to the embodiment of the present invention, wherein FIG. 9A is a process of softening a thermoplastic resin layer with a laser beam having a small diameter; Denotes a thin film transistor element peeling step by laser light irradiation, and (c) denotes a thin film transistor element holding step by a thermoplastic resin layer.
FIG. 10 is a process cross-sectional view illustrating an assembly process in the method for manufacturing a liquid crystal display device according to the embodiment of the present invention.
[Explanation of symbols]
10, 41, 51, 61, 101, 111, 121 First substrate
11, 43, 53, 63 103, 113, 123 Second substrate
12 elements
42, 52, 62, 79, 81, 82 Light emitting diode
102, 112, 122 Thin film transistor element
44, 54, 64, 104, 114, 124 Thermoplastic resin layer

Claims (25)

In the selective transfer method of an element for selectively transferring a part of elements from a plurality of elements on the first substrate onto the second substrate,
Forming a plurality of elements on the first substrate which is a light transmissive substrate ;
Forming a thermoplastic resin layer on the surface of the second substrate;
By utilizing ablation by irradiation of an energy beam transmitted through the first substrate at an interface on the first substrate side of the element or a peeling layer formed between the element and the first substrate, the plurality Selectively exfoliating some of the elements from the first substrate;
A step of selectively transferring the element to the second substrate by selectively holding the peeled element on the thermoplastic resin layer so that the peeled element enters the thermoplastic resin layer. A method for selectively transferring an element. The element selective transfer method according to claim 1, wherein the thermoplastic resin layer is formed of any one of polysulfone, aramid, polycarbonate, and thermoplastic polyimide. The thermoplastic resin layer in a region corresponding to the partial element is heated by irradiation with an energy beam before the step of selectively peeling the partial element from the first substrate . Element selective transfer method. 4. The element selective transfer method according to claim 3 , wherein the energy beam is a laser beam. Wherein the energy beam selection device transfer method according to claim 3, wherein the irradiation range is a range smaller than the diameter of the element to be transferred. 4. The element selective transfer method according to claim 3, wherein the second substrate is a light-transmitting substrate, and the thermoplastic resin layer is heated by irradiation with an energy beam transmitted through the second substrate. The element selective transfer method according to claim 1, wherein after selectively holding the element on the thermoplastic resin layer , each element is pressed against the second substrate by a pressure plate from the back side of the element. The element selective transfer method according to claim 7, wherein a release member is formed on a surface of the pressure plate. The device is light-emitting element, a liquid crystal control devices, photoelectric conversion elements, piezoelectric elements, thin-film transistor device, a thin film diode elements, resistor elements, according to claim 1 switching elements, micro-magnetic device, a selected element or portion thereof from the micro-optical element The selective transfer method of the element described. The element selective transfer method according to claim 1, wherein the element is a semiconductor light emitting element having a pointed portion, and the element is pressure-bonded to the thermoplastic resin layer from the pointed portion. The element selective transfer method according to claim 1, wherein the element is a semiconductor light emitting element having a pointed head, and a back surface of the semiconductor light emitting element on which the pointed head is formed is a substantially flat surface. 2. The element selective transfer method according to claim 1 , wherein the element is a nitride semiconductor element. In the selective transfer method of an element for selectively transferring a part of elements from a plurality of elements on the first substrate onto the second substrate,
Forming a plurality of elements each having a pointed head on a first substrate which is a light-transmitting substrate ;
Forming a thermoplastic resin layer on the surface of the second substrate;
By utilizing ablation by irradiation of an energy beam transmitted through the first substrate at an interface on the first substrate side of the element or a peeling layer formed between the element and the first substrate, the plurality Selectively exfoliating some of the elements from the first substrate;
The second element is formed by selectively holding the peeled element from the pointed side in the thermoplastic resin layer so that the pointed head of the peeled element enters the thermoplastic resin layer . A method of selectively transferring the element to a substrate. 14. The element selective transfer method according to claim 13, wherein the thermoplastic resin layer is formed of any one of polysulfone, aramid, polycarbonate, and thermoplastic polyimide. 14. The thermoplastic resin layer in a region corresponding to the partial element is heated by irradiation with an energy beam before the step of selectively peeling the partial element from the first substrate . Element selective transfer method. The element transfer method according to claim 15 , wherein the energy beam is a laser beam. Wherein the energy beam selection device transfer method according to claim 15, wherein the irradiation range is a range smaller than the diameter of the element to be transferred. The element selective transfer method according to claim 15, wherein the second substrate is a light-transmitting substrate, and the thermoplastic resin layer is heated by irradiation with an energy beam transmitted through the second substrate. The element selective transfer method according to claim 13 , wherein after selectively holding the element on the thermoplastic resin layer , each element is pressed against the second substrate by a pressure plate from the back side of the element. The element selective transfer method according to claim 19, wherein a release member is formed on a surface of the pressure plate. The method of claim 13 , wherein the element is a semiconductor light emitting element. The element selective transfer method according to claim 13, wherein the element is a semiconductor light emitting element, and a back surface of the semiconductor light emitting element on a side where the pointed portion is formed is a substantially flat surface. 14. The element selective transfer method according to claim 13 , wherein the element is a nitride semiconductor element. In the manufacturing method of an image display device for manufacturing an image display device by selectively transferring some of the light emitting devices from the plurality of light emitting devices on the first substrate onto the second substrate,
Forming a plurality of light emitting elements on the first substrate which is a light transmissive substrate ;
Forming a thermoplastic resin layer on the surface of the second substrate;
By utilizing ablation by irradiation of an energy beam transmitted through the first substrate at an interface of the light emitting element on the first substrate side , a part of the light emitting elements among the plurality of light emitting elements is selectively selected. Peeling from the first substrate;
The peeled light emitting element enters the thermoplastic resin layer, and the thermoplastic resin layer selectively holds the peeled light emitting element so that the second substrate can selectively hold the light emitting element. Repeat the transfer process,
A method for manufacturing an image display device, wherein each pixel arranged in a matrix is configured by adjoining light emitting elements having different emission wavelengths. In a liquid crystal display manufacturing method for manufacturing a liquid crystal display device by selectively transferring some thin film transistor elements from a plurality of thin film transistor elements on a first substrate onto a second substrate,
Forming a plurality of thin film transistor elements on the first substrate which is a light transmissive substrate ;
Forming a thermoplastic resin layer on the surface of the second substrate;
A part of the thin film transistors in the plurality of thin film transistor elements by utilizing ablation by irradiation of an energy beam transmitted through the first substrate in a peeling layer formed between the thin film transistor elements and the first substrate Selectively peeling the element from the first substrate;
The thin film transistor element is selectively held on the second substrate by selectively holding the peeled thin film transistor element on the thermoplastic resin layer so that the peeled thin film transistor element enters the thermoplastic resin layer. Repeat the transfer process,
A method of manufacturing a liquid crystal display device, wherein a thin film transistor element for controlling each pixel arranged in a matrix is formed for each pixel.

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