KR102385376B1 - Layout structure between substrate, micro LED array and micro vacuum module for micro LED array transfer using micro vacuum module and Method for manufacturing micro LED display using the same - Google Patents

Abstract

In the method of transferring a micro LED array using a micro-vacuum module according to the present invention, the micro-vacuum module is formed to communicate with a plurality of adsorption holes and the plurality of adsorption holes in direct contact with the micro LED to be transferred. Contacting the suction holes of the micro vacuum module on a mother substrate or a temporary substrate including a single or a plurality of vacuum passages and having a micro LED array in the form of a chip; forming a suction force by making a vacuum flow path communicating with the suction holes in contact with the micro LED array in a vacuum state, and peeling the micro LED array from the mother substrate or the temporary substrate using the vacuum; releasing the exfoliated micro LED array after aligning it on a target substrate on which a conductive transfer member is applied; Conducting all of the micro LED arrays having the same color or different colors by performing the peeling, aligning and releasing processes of the micro LED array on the same color or different color micro LED arrays formed on a different mother substrate or temporary substrate than before transferring the transfer member to a desired position on the target substrate coated thereon; and transforming the transfer member through an external force applying medium to physically contact the target substrate and the micro LED array aligned on the target substrate to electrically interconnect them.

Description

Layout structure between substrate, micro LED array and micro vacuum module for micro LED array transfer using the same and a micro LED display manufacturing method using the same micro vacuum module and Method for manufacturing micro LED display using the same}

The present invention relates to an RGB micro light emitting diode using vacuum suction power to easily transfer and connect various micro light emitting diodes formed in a chip or thin film type on a mother substrate on a mother substrate by using selective micro vacuum adsorption to easily transfer and connect them on a target substrate. It is about transfer and assembly method.

Conventional printable semiconductors include thin film transistors, micro LEDs, batteries, and memories. The semiconductors are formed on a hard mother substrate including silicon, SOI, and glass substrates through a general semiconductor process, and thereafter, various electronic It is common to transfer to a silicon, SOI, glass, plastic substrate, etc. corresponding to a desired target substrate using a device printing method.

Methods that have been mainly studied in the past include polymer stamping, methods of transferring semiconductors using electrostatic force and electromagnetic force.

In the case of using a polymer stamp, the types of devices that can be transferred are very limited as they are limited to, for example, low-efficiency horizontal microLEDs. Accordingly, there is a disadvantage in that the transfer yield is low.

When the electrostatic force transfer module is used, there is a disadvantage in that the transfer yield is low. In addition, there is a problem in that there is a risk of damage to the electronic device because a high voltage is applied to the device when the electrostatic force is formed.

In the case of using the electromagnetic force transfer module, it has a disadvantage in that the transfer yield is low because transfer must be performed at least twice. In addition, it has a problem that it cannot be used in a semiconductor having a size of 30 μm or less.

Micro LED is a micro light emitting body that emits light by itself without a color filter. There are no restrictions on size, shape, and resolution because the panel is made by attaching pieces of LED that emit light. However, it is difficult to apply to the current display industry, including large-scale TV production, because the transfer process of planting the micro-LED chip on the substrate takes a long time and the cost is too high.

Looking at the method of manufacturing a light emitting diode on a flexible substrate, after transferring the alloy layer to the light emitting diode device layer, eutectic bonding to the transfer substrate, fixing the device layer, and irradiating a laser to the rear surface of the sacrificial substrate, the light emitting diode device Although there may be a method including a step of separating the layer from the sacrificial substrate, a separate process for peeling the mother substrate and bonding between the temporary transfer substrate and the device layer is required, so the process is complex and unstable.

In the currently developed micro light emitting diode transfer technologies, it is difficult to selectively transfer such as line-by-line transfer or pixel-by-pixel transfer.

As described above, the transfer member used for bonding the micro LED and the target substrate has a disadvantage that it is impossible to perform the transfer process multiple times with the same transfer member due to the irreversible nature, that is, the property that it is impossible to return to the original state once deformed. do.

The present invention is to solve the problems of the prior art, and through the process of selectively controlling the vacuum state of the suction holes having a micrometer size bonded to the micro light emitting diode formed on the mother substrate or the temporary substrate An object of the present invention is to provide a method for transferring and assembling RGB micro light emitting diodes using vacuum suction force, in which only the micro light emitting diode device to be peeled from is separated from the mother substrate or temporary substrate using vacuum suction force and transferred to the target substrate.

In order to solve the above problems, in transferring the micro LED array using the micro-vacuum module according to the present invention, the micro-vacuum module includes a plurality of suction holes and the plurality of direct contact on the micro LED array to be transferred. Contacting the suction holes of the micro vacuum module on a first mother substrate or a temporary substrate including a vacuum flow path formed to communicate with the suction hole and having a micro LED array of one color among red, green, and blue in the form of a chip; The vacuum flow path connected to the suction holes in contact with the micro LED array of one color is created in a vacuum state to form a suction force, and the micro LED array of one color is selectively or collectively separated from the first mother substrate or temporary substrate using this. making; After aligning the exfoliated micro LED array on the target substrate to which the transfer member is applied, selectively or collectively releasing the array; The process of peeling, aligning, and releasing the micro LED array of one color is performed on a micro LED array of the same color as the micro LED array of one color or different from the first mother board or temporary board. transferring the micro LED array of one color among red, green, and blue color or the micro LED array of red, green, and blue color to a desired position on the target substrate coated with the transfer member by performing the same on the colored micro LED array; and electrically or physically interconnecting the target substrate and the micro LED array aligned on the target substrate by deforming the conductive transfer member through an external force applying medium.

The micro LED constituting the micro LED array is a thin film type micro LED or a chip type micro LED. And the thin film micro LED includes a thin film micro LED having a horizontal structure, a thin film micro LED having a flip chip structure, and a thin film micro LED having a vertical structure.

The micro LED is a red, green, blue, or red, green, and blue LED that is aligned and transferred collectively or selectively on a target substrate coated with a transfer member using the micro-vacuum module.

The external force applied while the transfer member and the micro LED array are stacked on the target substrate is any one of a group including heat, pressure, ultrasound, physical force, and van der Waals force.

The mother substrate is any one of a group including a substrate capable of growing GaAs, Sapphire, Si, Glass, and an inorganic light emitting diode layer.

The transfer member is any one of a conductive adhesive material including ACF, ACA, SOCF, and Solder, or a group of materials having an adhesive force that does not exhibit conductivity.

The target substrate is any one of a group including a substrate on which electrodes are patterned, a substrate on which semiconductor device arrays are formed, and a backplane.

Before selectively or collectively peeling the micro LED array of one color from the mother substrate or the temporary substrate using a micro vacuum module, in a state in which the micro LED array of one color formed on the mother substrate is turned over with the mother substrate included and forming the micro LED array of one color on the temporary substrate by removing the mother substrate and contacting the one-color micro LED array to the temporary substrate.

The temporary substrate is a substrate coated with a material (e.g. TRT, UV Tape) that can control the adhesion by the outside.

In the method for transferring and assembling RGB micro light emitting diodes using vacuum suction power according to the present invention, the red, blue and green micro light emitting diodes formed on a mother substrate are aligned and transferred to a desired position on a target substrate coated with a transfer member, respectively, and then, Through the process of deforming the transfer member by applying an external force using an arbitrary medium on the top of the transferred micro light emitting diodes, the physical bonding and electrical interconnection between the micro light emitting diodes and the target substrate are formed at the same time.

That is, each micro light emitting diode by aligning and connecting three primary color micro light emitting diodes or micro light emitting diodes of the same color formed on one integrated mother substrate or temporary substrate to different mother substrates or temporary substrates at a desired position on the target substrate It enables the implementation of RGB displays or LED patches that can be individually driven.

In the present invention, after cutting the chip-type micro LED including all RGB, which has been completed up to packaging, in the state including the mother substrate, and in the state of grinding the mother substrate, transfer it to the target substrate using a micro vacuum module and an external force applying body of a rolling method, and the target substrate to connect with

1 to 8 show a process of transferring a chip-type micro LED including all RGB completed up to packaging on a mother substrate according to an embodiment of the present invention.
9 to 45 illustrate a transfer process of a micro LED having a thin-film flip-chip structure according to another embodiment of the present invention.
46 to 74 illustrate a transfer process of a micro LED having a thin film type vertical structure according to another embodiment of the present invention.
75 to 83 illustrate experimental results for actually implementing the present invention.
84 to 89 describe the selective peeling process of the micro LED array using the micro vacuum module.
FIG. 90 illustrates a micro-vacuum module equipped with red, green, and blue-colored micro-LED arrays through selective peeling of the micro-LED array using the micro-vacuum module.
91 to 93 explain the spacing between the suction holes required to implement the micro LED display and the LED patch using the micro vacuum module.
94 to 96 show a state of selectively aligning and transferring microLED arrays on a plurality of target substrates coated with a transfer member after peeling the microLED arrays from a mother substrate or a temporary substrate at once using a micro vacuum module.
97 to 102 show a state of selectively aligning and transferring microLED arrays on a plurality of target substrates coated with a transfer member after peeling the microLED arrays from a mother substrate or a temporary substrate at once using a micro vacuum module.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art It is provided for complete information. In the drawings, like reference numerals refer to like elements.

In the present invention, all processes used in the process including the mother substrate on which the micro LED is formed, the target substrate on which the micro LED is transferred, the transfer member applied on the target substrate, and the external force applying medium that applies an external force to the micro LED transferred to the target substrate The elements are equally applied to both the chip-type micro LED and the thin-film micro LED.

In the present invention, the micro vacuum module to which the micro vacuum is attached is a process substrate having a first connection hole connected to an external pump module and a second connection hole connected to a vacuum control unit, and a suction hole in a state spaced apart from the bottom of the process substrate It has a base substrate formed thereon, and an intermediate layer in which a single to a plurality of vacuum passages are formed to correspond to the adsorption holes in a state disposed between the process substrate and the base substrate. That is, it is shown that the adsorption holes are disposed in communication with each other on the lower ends of the plurality of channel holes in a state where the intermediate layer in which the vacuum passage is formed between the process substrate and the base substrate serves as a support layer.

In this state, in order to selectively transfer for each vacuum flow path, a vacuum must be formed for each channel pattern or line pattern formed along a plurality of vacuum flow paths. Here, a structure connected to the vacuum flow path and the suction hole may be defined as a channel pattern or a line pattern.

Meanwhile, in order to separate the devices to be transferred on the target substrate by channel, the devices to be transferred must be lifted by the suction force transmitted through the suction holes existing in the channel. It should be designed within a range that does not affect the adsorption holes existing on the pattern.

The present invention is characterized in that red, green, and blue LEDs formed on a mother substrate or a temporary substrate are aligned and transferred on a target substrate on which a transfer member is selectively applied using a micro vacuum module.

That is, it enables the transfer of the micro LED array using the micro vacuum module through the arrangement structure between the mother board or temporary board, the target board, the micro LED array, and the micro vacuum module. By applying an external force to the LEDs and transforming the transfer member, the electrodes and LEDs formed on the target substrate are physically bonded and electrically interconnected to ultimately enable individual driving of micro LEDs on the target substrate. Implement an LED patch.

The basic concepts used in the present invention are as follows.

Micro LED refers to an inorganic light emitting diode with a size of 100 μm or less. The micro LED is divided into a chip type micro LED and a thin film type micro LED, and the thin film type micro LED is divided into a horizontal type, a flip chip, and a vertical type thin film micro LED.

The chip-type micro LED refers to an inorganic light emitting diode in a packaged state with a thickness of 50 μm or more and a size of 100 μm or less.

Thin-film micro LED refers to an inorganic light emitting diode with a thickness of 5 μm or less and a size of 100 μm or less.

A micro LED with a flip-chip structure is a micro LED in which both n and p contact pads are exposed on one plane of the LED chip and emit light toward the surface on which no electrodes are formed. On the other hand, the micro LED having a vertical structure is a micro LED in which n contact pad and p contact pad are exposed on mutually parallel planes of the LED chip, respectively.

The external force applied while the transfer member and the micro LED are stacked on the target substrate may be any one of a group including heat, pressure, ultrasound, physical force, van der Waals force, and roll.

The mother substrate may be any one of the group including GaAs, Sapphire, Si, Glass, and a substrate on which an inorganic light emitting diode layer can be grown.

The temporary substrate may be any one of a group including a substrate coated with an externally controllable material (e.g. TRT, UV Tape), a substrate on which an eutectic bonding layer is formed, and a copper plate for mechanical peeling.

The transfer member may be any one of a conductive adhesive material including ACF, ACA, SOCF, and Solder, or a group of materials having an adhesive force that does not exhibit conductivity.

The target substrate may be any one of a group including a substrate on which electrodes are patterned, a substrate on which semiconductor device arrays are formed, or a backplane. The target substrate may be flexible or rigid.

In the present invention, the transfer process is possible using the micro vacuum module regardless of the chip-type structure or the thin film-type structure.

The vacuum hole of the micro vacuum module is brought into contact with the surface of the red micro LED formed in the form of a chip on the mother board. The vacuum hole may refer to a hole array constituting the micro vacuum module.

The suction holes in contact with the micro LED array of one color are created in a vacuum state to form a suction force, and the micro LED array of one color is collectively or selectively peeled off from the mother or temporary board.

After aligning the exfoliated micro LED array on the target substrate on which the transfer member is applied, it is released collectively or selectively.

The red, green, and blue micro LED arrays are repeatedly subjected to the same peeling, aligning, and releasing processes of the micro LED array on the same or different color micro LED arrays formed on a different mother board or temporary board than before. An LED array or a micro LED array of one color is transferred collectively or selectively to a desired position on a target substrate coated with a transfer member.

By deforming the transfer member through an external force applying medium, the target substrate and the micro LED array aligned on the target substrate are physically brought into contact and electrically interconnected.

1 to 8, a process of transferring a chip-type micro LED including all RGB completed up to packaging on a mother substrate according to an embodiment of the present invention is shown.

First, referring to FIG. 1 , a chip-type micro LED including all three primary colors RGB that has been packaged up to packaging is formed on a mother substrate.

Referring to FIG. 2 , a chip-type micro LED including all three primary colors of RGB that has been ground by grinding the mother substrate to a thickness of several tens to several micrometers is shown.

Referring to FIG. 3 , the packaged chip-type micro LED is cut into a chip shape including a mother board. The cutting method may include laser cutting, wafer sawing, and plasma dicing. Meanwhile, even in the above process, the mother substrate may be polished to a thickness of several tens to several micrometers through grinding.

Thereafter, referring to FIG. 4 , the MAVA module, which is a micro vacuum module, is placed on the chip-type micro LED array.

Referring to FIG. 5 , in a state where the micro-vacuum module is positioned above the chip-type micro LED array, it is contacted with the chip-type micro LED, and then a vacuum is formed to lift the chip-type micro LED.

Referring to FIG. 6 , a process of aligning and transferring the transfer member onto a target substrate coated with a transfer member is shown using a micro vacuum module capable of selectively adsorbing a chip-type micro LED.

Referring to FIG. 7, the conductive transfer member is deformed in the process of finally pressing the chip-type micro LED transferred to the target substrate using an external force applying medium to electrically and physically connect the target substrate and the chip-type micro LED at the same time.

On the other hand, referring to FIG. 8 , in the present invention, an external force is applied to the transferred chip-type micro LEDs using a roll as an external force applying medium to deform the transfer member and connect the micro LEDs to the target substrate.

Existing micro LED technologies had a problem in that it was difficult to implement a large-area RGB display because pressure was applied to the entire area of the target substrate when the micro LED and the target substrate were interconnected. On the other hand, the present invention enables the realization of a large-area RGB display with much less pressure compared to the existing micro LED technologies because the pressure on the target substrate is applied linearly by pressing using a roll as described above. do.

Hereinafter, the transfer process of the thin-film flip-chip/vertical micro LED will be described in detail.

First, the transfer process of the micro LED of the thin-film flip-chip structure will be described.

An n-electrode and a p-electrode to be electrically connected to the n-contact pad and p-contact pad of each micro LED must be formed on the target substrate. That is, in the micro LED having a flip chip structure, the temporary substrate is coated with a material (e.g. TRT, UV Tape) that can control adhesion by the outside, and refers to a transfer substrate used to move the micro LED from the mother substrate to the target substrate.

9 to 11 , red, green, and blue LED layers are formed on the mother substrate. Form red, blue, and green μLED epitaxy layers on the first, second, and third mother substrates, respectively.

12 to 14 , the red, green, and blue LED layers are etched in a flip-chip form to form an ohmic contact layer. That is, it is shown that a plurality of μLEDs are formed by etching the LED layer after patterning.

A photosensitizer or UV-cured polymer is patterned on each Epitaxy layer in the form of an LED chip. The μLED Epitaxy layer is dry etched to form three-color μLEDs and the patterned photosensitizer or UV-cured polymer is removed.

15 to 16 , after attaching a temporary substrate to the surface of the green and blue LED layers, a laser is irradiated between the mother substrate and the LED layer to remove the mother substrate. The LED layer formed on the mother substrate is aligned and brought into contact with the temporary substrate in an inverted state including the mother substrate. In this case, an adhesive material for physical bonding between the LED layer and the temporary substrate may be applied on the temporary substrate.

Referring to FIG. 17 , after attaching a temporary substrate to the surface of the red LED layer, the mother substrate is removed through chemical etching. The removal of the mother substrate is performed through a wet etching method using a chemical solution.

The temporary substrate stacking may use a eutectic bonding method on the plurality of micro LEDs.

Referring to FIG. 18 , it shows the appearance of over-etching the temporary board under the red micro LED etched in the flip-chip form in which the contact pads face down.

19 to 20 , after attaching a temporary substrate to the green and blue thin-film flip-chip micro LED chips formed on the mother substrate, the mother substrate is removed using a laser.

Using Laser Lift Off, Wet Etching, CMP, etc., the mother substrate containing the three-color μLEDs is removed, and the μLEDs are formed upside down on a temporary substrate. That is, n-contact and p-contact are formed while being in the direction of the temporary substrate.

Referring to FIGS. 21 to 22 , the green and blue LED layers formed on the temporary substrate are etched in a flip-chip form to form an ohmic contact layer. A photosensitizer or UV-cured polymer is patterned in a p-contact shape on the chip-type μLEDs formed through dry etching, and then dry-etched to reveal the n-contact layer of each μLED chip and cured with the patterned photosensitizer or UV. remove the polymer. An Ohmic contact layer is formed on the n-contact layer and p-contact layer of all μLEDs.

23 to 25 , red, green, and blue thin-film flip-chip micro LEDs are shown inverted so that Ohmic Contact Layers are facing down on a temporary substrate.

26 to 27 , after attaching a transfer substrate to the thin-film flip-chip micro LEDs, the temporary substrate is removed, and green and blue flip-chip micro LEDs are formed on the transfer substrate.

28 to 30 , in a state in which the red, green, and blue LEDs of the thin-film flip-chip micro attached on the transfer substrate and the micro vacuum module are aligned, a vacuum is prepared to be applied.

Referring to FIGS. 31 to 33 , the micro-vacuum module is in contact with the red, green, and blue thin-film flip-chip micro LED array, and then the micro LEDs are attached in a state in which a vacuum is formed.

Referring to FIGS. 34 to 36 , the micro-vacuum module is in contact with the red, green, and blue thin-film flip-chip micro LED array, and then the micro LEDs are lifted in a vacuum forming state. This is done by making the suction holes of the micro vacuum module in contact with the surface of the micro LED formed in the form of a chip on the temporary substrate, and then making the suction holes in contact with the micro LEDs in a vacuum state to form a suction force. Have the process of stripping the LED.

37 to 39 , the red, green, and blue thin-film flip-chip micro LED arrays attached to the micro vacuum module and the target substrate on which the transfer member is placed are aligned.

40 to 42 , a state in which the red, green, and blue thin-film flip-chip micro LEDs are released from the micro-vacuum module to the target substrate by releasing the vacuum on the vacuum passages constituting the micro-vacuum module is shown.

43 shows a thin-film flip-chip micro LED array of three RGB primary colors implemented on a target substrate.

Referring to FIG. 44 , the transfer member is deformed by applying an external force to the RGB thin-film flip-chip micro LEDs transferred on the target substrate using an external force applying medium, and the micro LEDs and the target substrate are electrically and physically connected.

On the other hand, referring to Figure 45, by applying an external force to the transferred RGB thin-film flip-chip micro LEDs using a roll as an external force applying medium, the transfer member is deformed, and the micro LEDs and the target substrate are electrically and physically connected. looks like

The interconnection technology between the micro LED and the target substrate developed in the past brought the form of providing the micro LED on the target substrate coated with the transfer member and then pressing it through an external force applying medium with a flat bottom. Meanwhile, in the case of the conventional method, as the number of micro LED chips increases and the area of the micro LED display increases accordingly, the pressure required to interconnect the micro LED chips with the target substrate is proportional to the total area of the micro LED chips. It has been increasing, and there has been a great difficulty in implementing a large-area display such as a laptop computer or a television.

On the other hand, when using a roll to press the micro LEDs on the target substrate to which the transfer member is applied, as the roll moves over the micro LED chips, the pressure proceeds in the form of a line of the micro LED array, so external force is applied in the form of a flat bottom. Compared with the medium, there is an advantage that much less pressure is required to interconnect the micro LED chips of the same area with the target substrate. Therefore, if the micro LED chips are pressed using a roll, a large-area display can be implemented with a small amount of pressure.

Next, the transfer process of the micro LED of the thin film type vertical structure will be described.

46 to 48 , red, green, and blue LED layers are formed on the mother substrate.

49 to 50, after attaching a temporary substrate to the surface of the green and blue LED layers, a laser is irradiated between the mother substrate and the LED layer to remove the mother substrate.

51 to 53 , it is shown that the red, green, and blue LED layers are dry-etched to form a chip including a bridge.

Referring to FIG. 54 , a state in which the mother substrate under the red micro LED etched in the form of a chip is over-etched is shown.

55 to 57, red, green, and blue thin-film vertical micro LED arrays including bridges formed freestanding on the mother substrate or temporary substrate by partially etching the mother substrate or temporary substrate are shown.

58 to 60 , in a state in which the red, green, and blue thin-film vertical micro LEDs and the micro vacuum module attached to the mother board or the temporary board are aligned, a vacuum is prepared to be applied.

Referring to FIGS. 61 to 63 , the micro LEDs are attached in a state where a vacuum is formed after the micro vacuum module is in contact with the red, green, and blue thin film type vertical micro LED array.

Referring to FIGS. 64 to 66 , the micro-vacuum module is in contact with the red, green, and blue thin-film-type vertical micro LED array, and then the micro LEDs are lifted in a vacuum forming state. This is done by contacting the suction holes of the micro vacuum module to the surface of the micro LED formed in the form of a chip on the mother or temporary board, then making the suction holes in contact with the micro LEDs into a vacuum state to form a suction force, and using this Have the process of peeling the micro LEDs from the plate or temporary substrate.

67 to 69, after aligning the red, green, and blue thin film type vertical micro LED array attached to the micro vacuum module and the target substrate on which the transfer member is walked, on the vacuum passages constituting the micro vacuum module It shows the release of red, green, and blue thin-film vertical micro LEDs from the micro vacuum module to the target substrate by releasing the vacuum.

70 shows a thin film type vertical micro LED array of three RGB primary colors implemented on a target substrate.

Referring to FIG. 71, the transfer member is deformed by applying an external force to the RGB thin film type vertical micro LEDs transferred on the target substrate using an external force applying medium, and the micro LEDs and the target substrate are electrically and physically connected.

On the other hand, referring to Figure 72, by applying an external force to the transferred RGB thin film-type vertical micro LEDs using a roll as an external force applying medium, the transfer member is deformed, and the micro LEDs and the target substrate are electrically and physically connected. looks like

The interconnection technology between the micro LED and the target substrate developed in the past brought the form of providing the micro LED on the target substrate coated with the transfer member and then pressing it through an external force applying medium with a flat bottom. Meanwhile, in the case of the conventional method, as the number of micro LED chips increases and the area of the micro LED display increases accordingly, the pressure required to interconnect the micro LED chips with the target substrate is proportional to the total area of the micro LED chips. It has been increasing, and there has been a great difficulty in implementing a large-area display such as a laptop computer or a television.

On the other hand, when using a roll to press the micro LEDs on the target substrate to which the transfer member is applied, as the roll moves over the micro LED chips, the pressure proceeds in the form of a line of the micro LED array, so external force is applied in the form of a flat bottom. Compared with the medium, there is an advantage that much less pressure is required to interconnect the micro LED chips of the same area with the target substrate. Therefore, if the micro LED chips are pressed using a roll, a large-area display can be implemented with a small amount of pressure.

Referring to FIG. 73, it is shown that RGB thin film type vertical micro LEDs are encapsulated using an insulating film. After encapsulating the micro LEDs interconnected with the target substrate with an insulator, a through hole is formed on the upper surface of the micro LED in the area to be in contact with the electrode. The through hole may be used by a method such as photolithography or a laser.

Referring to FIG. 74, an upper electrode is formed on the encapsulated RGB thin film type vertical micro LEDs. The upper electrodes of the micro LEDs are formed on an insulator and finally sealed with an insulator.

75 shows a process of peeling a micro LED from a substrate using a micro vacuum module and an actual optical micrograph of the peeled micro LED.

76 shows a process in which the micro LED attached to the micro vacuum module is transferred to a target substrate made of electrodes and an actual optical micrograph of the transferred micro LED.

77 shows an actual scanning electron micrograph of a micro LED including a bridge formed in freestanding on a mother substrate.

78 shows the appearance of an actual micro-vacuum module including micro LEDs, hopper holes, and vacuum passages separated from the mother substrate.

79 is an optical micrograph and light emission of a red thin film micro LED that is transferred to a target substrate using a micro vacuum module and electrically and physically connected to the target substrate.

80 shows the light emitting state and I-V characteristics of the red thin film micro LED transferred to the target substrate using the micro vacuum module and electrically and physically connected to the target substrate.

81 shows the EL spectrum of the red thin film micro LED transferred to the target substrate and electrically and physically connected to the target substrate using the micro vacuum module.

82 shows an optical micrograph of a blue thin film micro LED including a bridge formed in freestanding on a temporary substrate.

83 shows a scanning electron micrograph of a blue thin film micro LED including a bridge formed freestanding on a temporary substrate.

The present invention should be able to selectively peel off one single color micro LED array among RGB of three primary colors using a micro vacuum module. Through this, when manufacturing an RGB micro LED display, it is possible to pick up each RGB micro LED array in the form of a line.

84 to 86 show a state in which red, green, and blue thin-film flip-chip microLED arrays are selectively peeled from a mother substrate or a temporary substrate using a micro vacuum module.

87 to 89 show a state of selectively peeling red, green, and blue thin-film vertical microLED arrays from a mother substrate or a temporary substrate using a micro vacuum module.

FIG. 90 shows a state in which micro LED arrays of three primary colors of RGB are attached to a micro vacuum module through selective peeling.

91 shows the correlation between the PPI of the micro LED display and the spacing between the suction holes of the micro vacuum module.

The correlation between the distance between the PPI of the micro LED display and the suction hole of the micro vacuum module is as follows.

Assuming that there is a square display of 1000 PPI, the size of one pixel of this display will be 25 μm according to the definition of 1000 PPI, “There are 1000 pixels in 1 inch diagonal”. And if it is assumed that the size of the red, green, and blue sub-pixel micro LEDs is a square of 5 μm in width and length, the interval between sub-pixels of the same color is 20 μm. And at this time, the required interval between the adsorption holes of the micro vacuum module is 20 μm or less.

92 shows the distance between the PPI for each electronic device to which the LED display is applied and the suction hole of the micro vacuum module expected accordingly.

According to the calculation method of FIG. 91, high-resolution TVs with 4K resolution or higher to which micro LEDs are applied, tablet PCs, smartphones, VRs, and the PPI, Pixel Pitch of the display required to implement each of the next-generation VR/AR currently under development, and the The required spacing between the suction holes of the micro vacuum module is as shown in FIG. 92 .

Accordingly, in order to realize high-definition AR/VR of 2500 ppi level from high-resolution TV with 4k resolution or higher using micro-vacuum module transfer of micro LED array, the distance between suction holes must be 5 μm or more and within 300 μm.

And considering the size of the micro LED chip developed so far, it seems that the size of the adsorption hole is expected to be between 5 μm and 100 μm.

93 shows the maximum value of the gap between the suction holes of the micro vacuum module capable of manufacturing the LED patch when the micro LED-based LED patch is implemented.

Existing LED cosmetic devices (for example, LED masks) irradiate light from a distance of 2 cm or more from human skin, so the amount of light is lost while the light emitted from the device reaches the skin. For this reason, the LED is driven with a higher power than necessary to produce more light than the amount of light required for actual phototherapy, and the amount of heat generated increases accordingly. Therefore, portability is poor and long-term phototherapy is impossible.

Micro LED-based LED patch irradiates light to the skin while it is attached to the skin at an ultra-close distance within 0 mm to 8 mm. The loss of light is much less. As a result, it requires less power and generates less heat compared to the existing beauty devices using LEDs. Also, due to the nature of the patch, the size is smaller than that of a cosmetic device using an existing LED. Therefore, the micro LED-based LED patch has excellent portability and is capable of not only short-time phototherapy but also long-term phototherapy.

If such a micro LED-based LED patch is implemented using a micro vacuum module, the number of LED patches that can be made from one LED wafer radically increases. Savings can be expected.

The distance between the suction holes required when implementing a micro LED-based LED patch using a micro vacuum module is shown in FIG. 93 .

First, it is assumed that the size of the micro LED chip is 100 μm, the radiation angle of the light emitted from the LED chip is 60˚, the thickness of the light distribution layer film is 1.85 mm, and the radius of the light emitted through the light distribution layer film is 5 times wider than before. At a distance of 1.85 mm from the micro LED, the radius of the light emitted from the micro LED is 1 mm, which is increased to 5 mm when the light dispersion layer is used.

When using the arrangement method in which the distance between LEDs is wide among the arrangement methods between LEDs currently used in the LED patch, such as arrangement 2, where the micro LEDs are placed on top of the micro LEDs, the distance between the micro LEDs is 8 mm turns out.

However, unlike displays, LED patches do not require high-resolution, dense LED arrays. (When implementing a micro LED-based LED patch, the distance between micro LEDs is expected to be about 10 μm or more.)

Since the distance between micro LEDs in the LED patch is the same as or larger than the gap between the suction holes of the micro vacuum module, in order to implement a micro LED-based LED patch using a micro vacuum module, a distance between the suction holes of 10 μm or more and within 8 mm is required.

Next, the present invention is characterized in that the LEDs formed on the mother substrate or the temporary substrate are selectively aligned and transferred onto a plurality of target substrates coated with a transfer member in a state in which the LEDs are peeled off at once using a micro vacuum module.

94 to 96 show a state in which microLED arrays are peeled from a mother substrate or a temporary substrate at once using a micro vacuum module, and then selectively aligned and transferred twice on a plurality of target substrates to which a transfer member is applied.

94 shows microLED arrays arranged on a mother substrate or a temporary substrate.

FIG. 95 shows a process of sequentially releasing microLED arrays twice on different substrates after pickup of the microLED arrays using a micro-vacuum module.

Referring to FIG. 96 , the suction holes for peeling the first microLED arrays are connected to the vacuum control unit through channel 1, and the suction holes for peeling the second microLED arrays are connected to the vacuum control unit through the channel 2 for vacuum. to form and release states. The diameter of the suction hole written in the drawing is 50 μm, but it can be adjusted to a value between 10 μm and 100 μm. Similarly, the separation distance between channels may have a value of 140 μm or more, and the channel width may have a value between 30 and 200 μm.

97 to 102 show a state of selectively aligning and transferring microLED arrays four times on a plurality of target substrates coated with a transfer member after peeling the microLED arrays from a mother substrate or a temporary substrate using a micro vacuum module.

97 shows microLED arrays arranged on a mother substrate or a temporary substrate.

98 shows a process of sequentially releasing microLED arrays 4 times sequentially on different substrates after picking up the microLED arrays using a micro vacuum module.

Referring to FIG. 99 , the suction holes for peeling the first microLED arrays are connected to the vacuum control unit through channel 1, the suction holes for peeling the second microLED arrays are connected to the vacuum control unit through the channel 2, and The suction holes for peeling the 3 microLED arrays are connected to the vacuum control unit through the channel 3, and the suction holes for peeling the fourth microLED arrays are connected to the vacuum control unit through the channel 4 to form and release a vacuum. do.

FIG. 100 is a partial enlarged view of FIG. 99, showing the diameter of the suction hole to which the microLED arrays are directly attached, and the separation distance between the suction holes. In addition, the spacing between the channels and the channel width are shown. In this embodiment, the diameter of the adsorption hole and the separation distance between the adsorption holes are set to 50 μm and 250 μm, respectively.

Meanwhile, the spacing between the channels and the channel width are set to 30 μm, respectively. Meanwhile, although the diameter of the suction hole written in the drawing is 50 μm, it can be adjusted to a value between 10 μm and 100 μm. Similarly, the separation distance between channels may have a value of 30 μm or more, and the channel width may have a value between 30 and 200 μm.

101 shows a cross-sectional representation of a process in which microLED arrays are released from channel 1 to channel 3.

If you look at the upper left corner, you can see that lines A-B along the vertical direction and lines C-D along the horizontal direction are displayed on the plane of a set of four microLED arrays.

If you look at the upper right, it shows the first release process on the A-B cross section, and shows the process of releasing the vacuum on channel 1 while maintaining the vacuum of the other channel to create an atmospheric pressure and transferring it on the target substrate.

Looking at the lower left side, the second release process is shown on the C-D cross section, showing the process of releasing the vacuum on the channel 2 while maintaining the vacuum of the other channel and transferring it on the target substrate.

Looking at the lower right, the third release process is shown on the A-B cross section, and the process of releasing the vacuum on the channel 3 while maintaining the vacuum of the other channel and transferring the vacuum on the target substrate is shown.

102 shows a state in which one set of four microLEDs is formed to form a 3x3 array.

Channels 1 and 2 respectively connected to the first and second microLED arrays are connected to each other in the micro-vacuum module, and channels 3 and 4 respectively connected to the first and second microLED arrays are micro-LED arrays. It is shown that the hoses connected from the vacuum module are connected at once from the outside of the micro vacuum module and are designed to hold the vacuum at once.

As described above, in the method for transferring and bonding micro light emitting diodes using vacuum suction power according to the present invention, red, blue, and green micro light emitting diodes formed on different mother substrates or temporary substrates are used as target substrates coated with a transfer member, respectively. After aligning and transferring to the location, the transfer member is deformed by applying an external force using an arbitrary medium on the top of the transferred micro light emitting diodes to achieve physical bonding and electrical interconnection between the micro light emitting diodes and the target substrate at the same time. it forms

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. That is, a person of ordinary skill in the art to which the present invention pertains can make numerous changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are possible. Equivalents are to be considered as falling within the scope of the present invention.

Claims (13)

delete delete In the arrangement structure between a mother substrate or a temporary substrate, a target substrate, a micro LED array, and a micro vacuum module for micro LED array transfer using a micro vacuum module,
The arrangement structure is
each mother substrate or temporary substrate on which red, green, and blue color micro LED arrays are formed; and
a target substrate coated with a transfer member; and
Including; a micro vacuum module for peeling the micro LED array from the mother substrate or the temporary substrate;
The micro vacuum module includes a plurality of adsorption holes exposed to the outside and a single or a plurality of vacuum passages for communicating the plurality of adsorption holes with each other, and maintaining an interval greater than or equal to the size of each adsorption hole between the plurality of adsorption holes do,
The micro-vacuum module forms a vacuum in some of the vacuum passages and in the suction holes subordinate to the partial vacuum passages to selectively or collectively select one color micro LED array from among the micro LED arrays from the mother substrate or temporary substrate. peel off hostilely,
The micro LED array provided in the micro-vacuum module is formed by forming a vacuum in a vacuum passage that communicates between the suction holes to which the micro LED array is not attached and the suction holes to which the micro LED array is not attached among the plurality of suction holes. By selectively or collectively peeling the micro LED arrays of different colors from different mother boards or temporary boards for each color, the micro vacuum module is equipped with all of the red, green, and blue micro LED arrays.
Characterized in that the red, green, and blue color micro LED array attached to the micro vacuum module is released to the target substrate by releasing the vacuum of the vacuum flow path in which the vacuum is formed and the suction holes subordinated thereto,
layout structure.
delete 4. The method of claim 3,
The width of the adsorption hole is 5 μm or more and less than 100 μm, and the interval between the suction holes is 5 μm or more and less than 300 μm, which enables the implementation of a single color or RGB micro LED display.
layout structure.
delete 6. The method of claim 5,
The transfer member is any one of a conductive adhesive material including ACF, ACA, and solder, and a material having an adhesive force that does not exhibit conductivity.
layout structure.
8. The method of claim 7
The transfer member may be deformed by an external force applying medium having a flat bottom surface or a roll shape.
layout structure.
delete delete delete delete delete

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