WO2021040391A1

WO2021040391A1 - Micro led transfer method

Info

Publication number: WO2021040391A1
Application number: PCT/KR2020/011362
Authority: WO
Inventors: 이창구
Original assignee: 주식회사 디플랫; 성균관대학교산학협력단
Priority date: 2019-08-29
Filing date: 2020-08-26
Publication date: 2021-03-04

Abstract

A micro LED transfer method according to an embodiment of the present invention comprises: a micro LED preparation step of preparing a loading substrate on which a micro LED is loaded; a pick-up step of adsorbing the top surface of the micro LED loaded on the loading substrate by a transfer head and separating the micro LED from the loading substrate; and an arrangement step of positioning the electrode part of the micro LED on a terminal part of a target substrate by the transfer head and arranging the micro LED on the target substrate by applying positive pressure to the transfer head.

Description

Micro LED transfer method

The present invention relates to a micro LED transfer method, and relates to a micro LED transfer method for quickly and stably transferring the micro LED to a target substrate.

Light-emitting diodes (LEDs) are widely used as products with high luminance and high power emission functions in the fields of lighting, electric signboards, traffic lights, and home appliances in the function of small display devices, and general LEDs used for lighting have a size of 1000 um * 1000 um. .

When the area of these LEDs is reduced to 1/100, they become 100 um * 100 um in size about the thickness of a hair. This is called micro LED, and it is emerging as a next-generation display.

Micro LED can form a side length of 1 to 100 um, and a flexible display can be implemented by transferring a micro LED of this size to a flexible substrate, and various industrial fields such as wearable displays and medical devices for human body insertion. It can be applied to.

In order to manufacture a micro LED display, micro LEDs must be transferred to a target substrate such as a flexible substrate. When implementing a micro LED display in 4K UHD (3840 * 2160), approximately 25 million micro LEDs are used as the target substrate. Since it must be transferred to and mounted, the speed, accuracy, and stability of the transfer process have a great influence on micro LED display products.

As a transfer method to transfer the micro LED to the target substrate, there is a method using an electrostatic head developed by Luxvue, USA. In this method, a micro LED is placed on the electrostatic head and a voltage is applied to the electrostatic head to connect the micro LED. Pick up and transfer to the target substrate. In the case of this method, since voltage is applied to the electrostatic head, there is a problem that damage to the micro LED occurs.

As another transfer method, there is a method of stamping micro LEDs using a high molecular material developed by X-Celeprint in the US as a printhead, picking up, and transferring. In this case, an adhesive layer to pick up the micro LEDs is required. , When repeating the transfer method, there is a problem that the adhesive strength decreases.

Accordingly, there is a need to develop a micro LED transfer method capable of improving the above-described problems and securing speed, accuracy, and stability of the transfer process.

The problem to be solved by the present invention is to provide a micro LED transfer method for quickly and stably transferring a micro LED to a target substrate.

Micro LED transfer method according to an embodiment of the present invention for solving the above problem is a micro LED preparing step of preparing a loading substrate on which the micro LED is loaded; A pickup step of adsorbing the upper surface of the micro LED loaded on the loading substrate with a transfer head and separating the micro LED from the loading substrate; And an arrangement step in which the transfer head locates the electrode portion of the micro LED at a terminal portion of a target substrate, and applies a positive pressure to the transfer head to place the micro LED on the target substrate. Including, the elastic modulus of the transfer head may be implemented in 0.00036 ~ 5.5 GPa.

In addition, the step of preparing the micro LED may include a preparation step of disposing a plurality of micro LEDs located on an upper surface of the electrode unit to be spaced apart from each other on a separation substrate; And a loading step of inverting the separation substrate to load the micro LED so that the electrode part faces the loading substrate, and separating the micro LED from the separation substrate. It may include.

In addition, the preparation step may include a diode forming step of forming a diode by laminating an n layer, a light emitting layer, and a p layer on a growth substrate; A separating substrate laminating step of laminating the separating substrate on the p-layer; A growth substrate separation step of separating the growth substrate from the diode and inverting the separation substrate; And a micro LED processing step of processing the diode into a micro LED. It may include.

In addition, the separation substrate may be implemented as a thermal peeling tape or a UV peeling tape.

In addition, the loading substrate may be implemented as a PDMS film or an elastomer film.

In addition, the loading substrate may be implemented by any one of a polymer tape, a glass substrate, a polymer coated glass substrate, a SiC substrate, a GaAs substrate, a Si substrate, or a sapphire substrate.

In addition, the loading step may include a micro LED arranging step in which the electrode portion of the micro LED is in contact with the loading substrate; And a micro LED separating step of separating the micro LED from the separating substrate by applying heat or UV to the separating substrate. It may include.

In addition, the loading substrate includes: a loading die having a plurality of receiving grooves for accommodating one micro LED chip, and having a first chamber formed therein; A first through hole formed in the receiving groove and communicating with the first chamber; And a vacuum module for applying a negative pressure to the first chamber. It may include.

In addition, the loading step may include a micro LED arranging step of arranging the electrode part of the micro LED to be seated in the receiving groove of the loading die; And a micro LED separating step of separating the micro LED from the separating substrate by applying a negative pressure to the first chamber to fix the micro LED in the receiving groove and then applying heat or UV to the separating substrate. It may include.

In addition, the transfer head may include a transfer head body having a second chamber formed therein; A gripper provided to protrude from the transfer head body to contact the micro LED; A second through hole formed to pass through the gripper and communicating with the second chamber; And a pressure applying module for applying a negative or positive pressure to the second chamber. It may include.

In addition, in the pickup step, a negative pressure is applied to the second chamber, so that the micro LED may be adsorbed by the gripper.

In addition, the transfer head may adsorb one micro LED of the plurality of micro LEDs loaded on the loading substrate, and other micro LEDs adjacent to the adsorbed micro LEDs may remain on the loading substrate.

In addition, the loading step is a micro LED separating step of separating the micro LED from the separating substrate by applying a negative pressure to the first chamber to fix the micro LED in the receiving groove and then applying heat or UV to the separating substrate. It may include.

In addition, in the pickup step, an absolute value of the sound pressure applied to the second chamber may be applied to a value greater than an absolute value of the sound pressure applied to the first chamber.

In addition, an electrically conductive ink may be applied to the terminal portion of the target substrate.

In addition, the gripper may have an inclined surface formed on the outer circumferential surface.

In addition, the transfer head may be made of at least one of polycarbonate, polyurethane, urethane acrylate, isobornyl acrylate, epoxy, and PDMS.

According to the micro LED transfer method according to an embodiment of the present invention, the micro LED 20 can be quickly, accurately and stably transferred to the target substrate 60.

1 is a flow chart of a micro LED transfer method according to an embodiment of the present invention.

2 is an embodiment of a preparation step (S11) according to the present invention.

3 is an embodiment of the loading step (S12) according to the present invention.

Figure 4 is another embodiment of the loading step (S12) according to the present invention.

5 is an embodiment of a pickup step (S20) according to the present invention.

6 is another embodiment of the pickup step (S20) according to the present invention.

7 is an embodiment of the arrangement step (S30) according to the present invention.

Figure 8 (a) is a gripper 539 according to an embodiment of the present invention, Figure 8 (b) is a gripper 539 according to another embodiment of the present invention.

9 is an embodiment of a micro LED display 1 manufactured according to embodiments of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals shown in each drawing indicate the same member.

Hereinafter, a micro LED transfer method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 8.

Figure 1 is a flow chart of a micro LED transfer method according to an embodiment of the present invention, Figure 2 is an embodiment of a preparation step (S11) according to the present invention, Figure 3 is a loading step (S12) according to the present invention In one embodiment, Figure 4 is another embodiment of the loading step (S12) according to the present invention, Figure 5 is an embodiment of the pickup step (S20) according to the present invention, Figure 6 is a pickup according to the present invention It is another embodiment of step (S20), Figure 7 is an embodiment of the arrangement step (S30) according to the present invention, Figure 8 (a) is a gripper 539 according to an embodiment of the present invention, 8B is a gripper 539 according to another embodiment of the present invention.

Referring to Figures 1 to 8, the micro LED transfer method according to an embodiment of the present invention, a micro LED preparation step (S10) of preparing a loading substrate 40 on which the micro LED 20 is loaded, a loading substrate ( 40) A pickup step (S20) of adsorbing the upper surface of the micro LEDs 20 loaded on the transfer head 50 and separating the micro LEDs 20 from the loading substrate 40, and the transfer head 50 Arrangement in which the electrode part 21 of the LED 20 is placed on the terminal part 61 of the target substrate 60, and the micro LED 20 is placed on the target substrate 60 by applying positive pressure to the transfer head 50 It includes step S30.

In the micro LED preparation step (S10), the loading substrate 40 on which the micro LED 20 is loaded is prepared.

The micro LED 20 may be formed by growing a plurality of thin films of inorganic materials such as Al, Ga, N, P, and As In on a sapphire substrate or a silicon substrate, and then cutting and separating a sapphire substrate or a silicon substrate. Here, the sapphire substrate or the silicon substrate functions as the growth substrate 30.

The micro LED 20 may be formed in a maximum size of 100 um * 100 um. The micro LED 20 may be formed in a square or rectangular shape. At this time, the length of the side of the micro LED 20 may be formed of 1 ~ 100 um.

As described above, since the micro LED 20 is formed in a fine size, it can be transferred to a flexible substrate such as plastic, and thus a flexible display device can be manufactured.

In addition, unlike the organic light emitting layer, the micro LED 20 is formed by growing a thin film of an inorganic material, so that the manufacturing process is simple and the yield is improved. In addition, since the micro LEDs 20 separated individually are transferred onto a large-area substrate, it is possible to manufacture a large-area display device.

In the micro LED preparation step (S10), the loading substrate 40 on which the micro LED 20 is mounted on the surface may be provided. In this case, in this case, in the micro LED preparation step (S10), a plurality of micro LEDs 20 may be provided on the loading substrate 40 in a state in which the plurality of micro LEDs 20 are disposed to be spaced apart from each other. In addition, in the micro LED preparation step (S10), the micro LED 20 may be loaded on the surface of the loading substrate 40 to prepare the loading substrate 40 on which the micro LED is loaded. The micro LED 20 provided on the loading substrate 40 in the micro LED preparation step S10 may be picked up in the pickup step S20 to be described later.

Here, the micro LED preparation step (S10) according to an embodiment of the present invention is a preparation step of disposing the plurality of micro LEDs 20 on which the electrode part 21 is located on the upper surface to be spaced apart from each other ( S11), a loading step of inverting the separation substrate 10 to load the micro LEDs 20 so that the electrode part 21 faces the loading substrate 40, and to separate the micro LEDs 20 from the separation substrate 10 (S12) is included.

In the preparation step (S11), the plurality of micro LEDs 20 on which the electrode part 21 is located on the upper surface are arranged to be spaced apart from each other on the separation substrate 10.

In the preparation step (S11), a plurality of micro LEDs 20 are disposed on the separation substrate 10. A plurality of micro LEDs 20 may be disposed on the separation substrate 10. The plurality of micro LEDs 20 may be disposed to be spaced apart from each other. The micro LED 20 may be disposed such that the electrode part 21 is positioned on the upper surface. In this case, as shown in (d) of FIG. 2, the electrode portion 21 of the micro LED 20 is positioned on the upper surface of the separator plate 10. This will be described later.

One type of micro LED 20 is disposed on the separator plate 10. The micro LED 20 may be implemented in any one of R (red), G (green), and B (blue) emitting one color according to an embodiment, and in an embodiment of the present invention, the separation substrate 10 The micro LED 20 disposed in is implemented in any one of R, G, and B.

The separation substrate 10 may be implemented with a thermal peeling tape or a UV peeling tape. In the loading step (S12) to be described later, when the separation substrate 10 is implemented as a thermal release tape, when heat is applied to the thermal release tape, it may be separated from the contacted object, the micro LED 20. . When the separating substrate 10 is a UV release tape, when UV is applied to the UV release tape, it may be separated from the micro LED 20 which is a contacted object.

Here, the preparation step (S11) according to an embodiment of the present invention is a diode formation step (S111) of stacking the n-layer 23, the light-emitting layer 25, and the p-layer 27 on the growth substrate 30 to form a diode (S111). ), a separation substrate lamination step (S112) of stacking the separation substrate 10 on the p-layer 27, a growth substrate separation step (S113) of separating the growth substrate 30 from the diode and inverting the separation substrate 10 (S113) , And a micro LED processing step (S114) of processing the diode into the micro LED (20).

First, as shown in FIG. 2A, in the diode formation step S111, the n-layer 23, the light-emitting layer 25, and the p-layer 27 are stacked on the growth substrate 30 to form a diode.

The growth substrate 30 may be implemented as a sapphire substrate or a silicon substrate, but the embodiment is not limited thereto.

The n-layer 23 and p-layer 27 are an n-type semiconductor layer and a p-type semiconductor layer, respectively. The light-emitting layer 25 is an active layer, and is a region in which electrons and holes are recombined. As the electrons and holes recombine, the light-emitting layer 25 may transition to a low energy level and generate light having a wavelength corresponding thereto.

The n-layer 23, the light-emitting layer 25, and the p-layer 27 are sequentially stacked on the growth substrate 30. The diode formed of the n-layer 23, the light-emitting layer 25, and the p-layer 27 may be formed by a known technique. The diode can be fabricated into a micro LED 20, as described below.

In the separating substrate stacking step (S112), the separating substrate 10 is stacked on the p-layer 27 as shown in FIG. 2A. The separation substrate 10 may be stacked on the upper surface of the p-layer 27. Separation substrate 10 may be implemented as a thermal peeling tape or UV peeling tape as described above.

In the growth substrate separation step (S113), the growth substrate 30 is separated from the diode, and the separation substrate 10 is inverted. First, the growth substrate 30 may be separated from the diode. In this case, the growth substrate 30 may be separated from the diode by a known method. For example, when the growth substrate 30 is a sapphire substrate, it may be performed by a laser lift off (LLO) method of separating the sapphire substrate by irradiating a laser between the sapphire substrate and the n-layer 23. In addition, when the growth substrate 30 is a silicon substrate, it may be performed by a chemical lift off (CLO) method in which the silicon substrate and the n-layer 23 are separated by etching.

When the growth substrate 30 is separated from the diode, the separation substrate 10 is inverted. In this case, as shown in (b) of FIG. 2, the separator plate 10 is positioned at the bottom, and the diode is positioned at the top. In this case, a p-layer 27, a light-emitting layer 25, and an n-layer 23 are arranged on the upper surface based on the separation substrate 10 in this order.

Depending on the embodiment, in the step of separating the growth substrate (S113), the separation substrate 10 may be inverted and the growth substrate 30 may be separated from the diode.

In the micro LED processing step (S114), the diode is processed into the micro LED 20. In this case, as shown in Fig. 2(c), an electrode part 21 is formed on the diode.

In this case, the electrode part 21 may be formed on the upper surfaces of the n-layer 23 and p-layer 27 by a known method. Here, the n-layer 23 and the light-emitting layer 25 are partially etched, and the p-layer 27 remains in its original state, so that the electrode part 21 is formed on the upper surfaces of the n-layer 23 and the p-layer 27. Can be formed. At this time, the lower surface of the p-layer 27 is a surface to which the separator plate 10 is in contact, and a non-electrode surface on which no electrode is formed is formed.

After the electrode portions 21 are formed on the upper surfaces of the n-layer 23 and p-layer 27, the p-layer 27 is diced as shown in FIG. 2(d). The p-layer 27 may be diced by a known method such as wet etching, dry etching, or laser cutting. In this case, it may be diced by a plasma dry etching method. When the p-layer 27 is diced, the diode is processed into the micro LED 20. Accordingly, a plurality of micro LEDs 20 are disposed on the separation substrate 10 to be spaced apart from each other. At this time, the micro LED 20 may have a side length of 1 to 100 um.

Above, in the preparation step (S11) according to the above-described process, a plurality of micro LEDs 20 are disposed to be spaced apart on the separation substrate 10. Further, the electrode portion 21 is disposed on the upper surface of the n-layer 23 and the upper surface of the p-layer 27, and the electrode portion 21 is disposed on the upper surface of the micro LED 20.

In the loading step (S12), the separation substrate 10 is reversed to load the micro LED 20 so that the electrode part 21 faces the loading substrate 40, and the micro LED 20 is removed from the separation substrate 10. Separate.

In the loading step (S12), based on Figures 3 (a) and 4 (a), the separation substrate 10 so that the separation substrate 10 is located at the top and the micro LED 20 is located at the bottom, Reverse. In this case, the electrode portion 21 of the micro LED 20 is disposed to face the mounting substrate 40. At this time, since the electrode part 21 of the micro LED 20 is disposed toward the loading substrate 40, it is located at the lower side.

Thereafter, the micro LED 20 is in contact with the loading substrate 40. At this time, the electrode part 21 is in contact with the loading substrate 40. Accordingly, the micro LED 20 is loaded on the loading substrate 40.

After the micro LED 20 is loaded on the loading substrate 40, the micro LED 20 is separated from the separating substrate 10. The micro LED 20 may be separated in various ways according to the embodiment of the loading substrate 40. When the micro LED 20 is separated from the separating substrate 10, the separating substrate 10 is separated and the micro LED 20 is completely seated and loaded on the loading substrate 40. Accordingly, the micro LED 20 can be provided on the loading substrate 40.

Here, the loading substrate 40 according to an embodiment of the present invention may be implemented with a PDMS film 41 or an elastomer film 41.

The PDMS film 41 is made of polydimethyl siloxane (PDMS), has low surface tension, excellent surface smoothness, high chemical stability, excellent heat resistance, and moldability.

The elastomer film 41 is a polymer material exhibiting rubber elasticity at room temperature, and includes at least one of a thermoplastic elastomer, an elastic fiber, and a foam in addition to vulcanized natural rubber and synthetic rubber.

Since the loading substrate 40 is implemented with the PDMS film 41 or the elastomer film 41, the micro LED 20 can be stably loaded on the loading substrate 40.

In addition, since the electrode part 21 is loaded on the non-conductive and elastic PDMS film 41 or the elastomer film 41, the electrode part 21 can be protected from static electricity or physical impact.

In addition, the loading substrate 40 according to an embodiment of the present invention may be implemented by any one of a polymer tape, a glass substrate, a polymer coated glass substrate, a SiC substrate, a GaAs substrate, a Si substrate, and a sapphire substrate. have. Accordingly, the micro LED 20 on the loading substrate 40 can be stably loaded on the loading substrate 40.

In this case, the loading step (S12) according to an embodiment of the present invention is a micro LED arranging step (S121) in which the electrode portion 21 of the micro LED 20 is placed in contact with the loading substrate 40 (S121), and the separating substrate It includes a micro LED separation step (S122) of separating the micro LED 20 from the separation substrate 10 by applying heat or UV to (10).

In the micro LED arranging step (S121), the micro LED 20 is disposed on the loading substrate 40. At this time, as described above, the electrode portion 21 of the micro LED 20 is disposed to be in contact with the loading substrate 40.

Thereafter, in the micro LED separation step (S122), heat or UV is applied to the separation substrate 10. Here, when the separation substrate 10 is implemented with a thermal release tape, heat is applied, and when implemented with a UV release tape, UV is applied. Heat or UV may be applied between the separator plate 10 and the micro LED 20. At this time, heat or UV may be applied to the non-electrode surface of the p-layer 27.

Accordingly, the micro LED 20 is separated from the separating substrate 10, and the micro LED 20 is completely seated and loaded on the loading substrate 40 as shown in FIG. 3(b). Finally, the loading substrate 40 on which the micro LED 20 is loaded is provided.

Meanwhile, the loading substrate 40 according to another embodiment of the present invention has a plurality of receiving grooves 431 for accommodating one micro LED 20 as shown in FIG. 4, and a first chamber 435 therein The formed loading die 43, the first through hole 433 formed in the receiving groove 431, communicated with the first chamber 435, and a vacuum module 437 for applying a negative pressure to the first chamber 435 Includes.

As for the stacking die 43, a plurality of receiving grooves 431 are formed in the stacking die 43 as shown in FIGS. 4A and 4B. One receiving groove 431 accommodates one micro LED (20). The receiving groove 431 is formed by being recessed. The receiving groove 431 is formed to correspond to the size of the micro LED 20.

A first chamber 435 of a cavity is formed in the loading die 43. The first chamber 435 communicates with the first through hole 433.

A first through hole 433 is formed in the receiving groove 431. In this case, a first through hole 433 is formed for each receiving groove 431. The first through hole 433 communicates with the first chamber 435.

Depending on the embodiment, the receiving groove 431 and the first through hole 433 may be processed by MEMS, laser, or precision machining, but the embodiment is not limited thereto.

The vacuum module 437 creates a negative pressure in the first chamber 435. When negative pressure is formed in the first chamber 435, a vacuum is formed in the first chamber 435. In this case, a suction force is generated in the first through hole 433 communicated with the first chamber 435, and the micro LED 20 loaded in the receiving groove 431 is adsorbed into the receiving groove 431. When the micro LED 20 is adsorbed in the receiving groove 431, the micro LED 20 is fixed to the receiving groove 431.

In this case, the loading step (S12) according to another embodiment of the present invention is a micro LED arranging step of arranging the electrode part 21 of the micro LED 20 to be seated in the receiving groove 431 of the loading die 43 (S121), and by applying a negative pressure to the first chamber 435 to fix the micro LED 20 in the receiving groove 431, and then applying heat or UV to the separation substrate 10 It includes a micro LED separation step (S122) for separating the LED 20.

In the micro LED arranging step (S121), the micro LED 20 is disposed to be seated in the receiving groove 431 of the loading die 43. At this time, the electrode part 21 of the micro LED 20 is disposed to be seated in the receiving groove 431. In this case, the electrode portion 21 of the micro LED 20 may be disposed to be in contact with the loading die 43.

In the micro LED separation step (S122), a negative pressure is applied to the first chamber 435. In this case, as described above, the vacuum module 437 creates a negative pressure in the first chamber 435 so that a vacuum is formed in the first chamber 435. The negative pressure applied to the first chamber 435 is not released and the applied state can be maintained. In this case, a suction force is generated in the first through hole 433 communicated with the first chamber 435, so that the micro LED 20 loaded in the receiving groove 431 is sucked into the receiving groove 431 and fixed.

Thereafter, heat or UV is applied to the separation substrate 10. Here, when the separation substrate 10 is implemented with a thermal release tape, heat is applied, and when implemented with a UV release tape, UV is applied. At this time, since a suction force is generated in the first through hole 433 to fix the micro LED 20 in the receiving groove 431, the position change or angle change when the micro LED 20 is separated from the separation substrate 10 It will not occur.

Accordingly, the micro LED 20 is separated from the separating substrate 10, and the micro LED 20 is completely seated and loaded on the loading die 43, as shown in FIG. 4(b).

In the pickup step (S20), the upper surface of the micro LED 20 loaded on the loading substrate 40 is adsorbed by the transfer head 50 as shown in FIGS. 5A and 6A, and the micro LED 20 ) Is separated from the loading substrate 40.

The transfer head 50 adsorbs the upper surface of the micro LED 20 loaded on the loading substrate 40. In this case, the p-layer 27 is positioned on the upper surface of the micro LED 20 in a state loaded on the loading substrate 40. That is, since the electrode part 21 is disposed downward in the loading step (S12), the n-layer 23 and the p-layer 27 on which the electrode part 21 is formed are located on the lower surface, and the p-layer 27 is formed on the upper surface. The non-electrode surface is located.

Accordingly, since the transfer head 50 adsorbs the non-electrode surface of the micro LED 20 on which the electrode part 21 is not formed, it does not give an electric or physical impact to the electrode part 21, so that the transfer quality of the micro LED Improves.

The transfer head 50 according to an embodiment of the present invention may be manufactured by known 3D printing. In this case, the material of the transfer head 50 according to an embodiment of the present invention may be made of plastic or silicon.

The modulus of elasticity of the transfer head 50 according to an embodiment of the present invention may be 0.00036 to 5.5 GPa.

Specifically, the material of the transfer head 50 according to an embodiment of the present invention is polycarbonate (PC), polyurethane, urethane acrylate, isobornyl acrylate. , Epoxy (Epoxy) and PDMS (polydimethylsiloxane, polydimethylsiloxane) may be selected and carried out at least one of.

At this time, the modulus of elasticity of polycarbonate (PC) is 2.0 to 2.6 GPa, the modulus of polyurethane is 0.5 to 5.5 GPa, the modulus of urethane acrylate is 2.5 to 3.0 GPa, isobor The modulus of elasticity of Isobornyl Acrylate may be 0.25 to 0.35 GPa, the modulus of elasticity of Epoxy is 3 GPa, and the modulus of elasticity of PDMS may be 0.00036 to 0.00087 GPa.

Accordingly, since the transfer head 50 can be elastically deformed, the transfer head 50 can be in close contact with the surface of the micro LED when the micro LED is adsorbed, and pick-up yield compared to the transfer head made of inelastic material. Can improve.

Thereafter, as shown in FIGS. 5B and 6B, the transfer head 50 separates the micro LED 20 from the loading substrate 40 in a state in which the micro LED 20 is adsorbed. That is, the transfer head 50 moves while the micro LEDs 20 are adsorbed to the adsorption head, so that the micro LEDs 20 are separated from the loading substrate 40.

Here, the transfer head 50 according to an embodiment of the present invention is provided to protrude a plurality of the transfer head body 531 and the transfer head body 531 in which the second chamber 535 is formed, and the micro LED 20 The pressure to apply negative or positive pressure to the gripper 539 in contact with the gripper 539, the second through hole 533 communicated with the second chamber 535 and formed to penetrate the gripper 539, and the second chamber 535 It includes an application module 537.

The transfer head body 531 forms an exterior. A second chamber 535 of a cavity is formed inside the transfer head body 531. The second chamber 535 communicates with a second through hole 533 to be described later.

The gripper 539 is provided on the transfer head body 531. A plurality of grippers 539 are formed. The gripper 539 is formed to protrude from the transfer head body 531. The gripper 539 is in contact with the micro LED 20. In this case, the gripper 539 may contact the non-electrode surface of the p-layer 27 of the micro LED 20 in the pickup step S20.

The second through hole 533 is formed to penetrate through the gripper 539. In this case, a second through hole 533 may be formed for each gripper 539. The second through hole 533 communicates with the second chamber 535.

The second through hole 533 may have a micro size. In this case, the size of the second through hole 533 is formed to have a length smaller than the length of the side of the micro LED 20.

Depending on the embodiment, the gripper 539 and the second through hole 533 may be processed by MEMS, laser, or precision machining, but the embodiment is not limited thereto.

The pressure applying module 537 forms a negative pressure or a positive pressure in the second chamber 535.

When negative pressure is formed in the second chamber 535 by the pressure applying module 537, a vacuum is formed in the second chamber 535. In this case, a suction force is generated in the second through hole 533 communicated with the second chamber 535, and the micro LED 20 in contact with the gripper 539 is adsorbed. When the micro LED 20 is adsorbed on the gripper 539, the micro LED 20 is adsorbed on the transfer head 50.

Accordingly, the transfer head 50 absorbs the non-electrode surface of the micro LED 20 on which the electrode portion 21 is not formed by vacuum, so that an electric shock is not applied to the electrode portion 21, and the transfer quality of the micro LED Improves.

Conversely, when positive pressure is formed in the second chamber 535 by the pressure applying module 537, the micro LED 20 is separated from the gripper 539. This will be described later.

Here, in the pickup step (S20) according to an embodiment of the present invention, a negative pressure is applied to the second chamber 535 to adsorb the micro LED 20 by the gripper 539. As described above, when a negative pressure is applied to the second chamber 535, the second chamber 535 forms a vacuum, and the micro LED 20 in contact with the gripper 539 is in the second through hole 533. It is adsorbed to the gripper 539 by the generated suction force. At this time, the gripper 539 may adsorb the non-electrode surface of the p-layer 27 that is the opposite surface of the electrode part 21 of the micro LED 20.

On the other hand, the transfer head 50 according to an embodiment of the present invention adsorbs one micro LED 20 among a plurality of micro LEDs 20 loaded on the loading substrate 40, and the adsorbed micro LED 20 Other micro LEDs 20 adjacent to are placed on the loading substrate 40.

That is, as shown in (a) of FIG. 5 or (a) of FIG. 6, when the transfer head 50 adsorbs a plurality of micro LEDs 20 loaded on the loading substrate 40, one micro LED 20 By adsorbing, the other micro LEDs 20 adjacent to the adsorbed micro LEDs 20 jump over and remain on the loading substrate 40 as they are.

For example, when adsorbing the first micro LED 20a of FIG. 5 (a) or 6 (a), the second micro LED 20b adjacent to the adsorbed first micro LED 20a is loaded It remains on the substrate 40 as it is, and the third micro LED 20c is adsorbed. In this case, the transfer head 50 may adsorb only the odd-numbered micro LEDs 20, and the even-numbered micro LEDs 20 may remain. In addition, according to an embodiment, the transfer head 50 may adsorb only the even-numbered micro LEDs 20, and the odd-numbered micro LEDs 20 may remain.

In the micro LED display 1, R, G, and B micro LEDs 20 that emit monochromatic light in each pixel area P must be mounted on the target substrate 60. Each pixel area P is formed to be physically spaced apart. At this time, since only one type of the R, G, and B micro LEDs 20 that emit light, for example, the R micro LEDs 20, is loaded on the loading substrate 40 of the present invention, each pixel area P is equipped with R micro LEDs. Only (20) can be transferred.

In this case, the transfer head 50 of the present invention adsorbs one micro LED 20, and the micro LED 20 adjacent to the adsorbed micro LED 20 remains on the loading substrate 40, and the loading substrate ( The micro LEDs 20 adjacent to the micro LEDs 20 residing on 40 are adsorbed again, so that one type of micro LEDs 20 is transferred to each pixel area P of the target substrate 60.

According to an embodiment, when the loading substrate 40 of the present invention is implemented in the embodiment of FIG. 4, in the pickup step (S20), the absolute value of the sound pressure applied to the second chamber 535 is the first chamber 435 It should be applied with a value greater than the absolute value of the sound pressure applied to.

That is, when negative pressure is applied to the first chamber 435 and the micro LED 20 is adsorbed and fixed to the receiving groove 431 of the loading die 43, the micro LED 20 in the pickup step (S20) In order to disengage from the loading die 43, the adsorption force applied to the transfer head 50 must be greater than the adsorption force applied to the receiving groove 431.

In this case, the absolute value of the sound pressure applied to the second chamber 535 is applied to a value greater than the absolute value of the sound pressure applied to the first chamber 435, so that the adsorption force applied to the transfer head 50 is applied to the receiving groove. It is to be formed larger than the adsorption force applied to (431). Accordingly, the micro LED 20 is adsorbed to the gripper 539, adsorbed to the transfer head 50, and separated from the loading die 43.

In the arrangement step (S30), the transfer head 50 places the electrode part 21 of the micro LED 20 on the terminal part 61 of the target substrate 60, and applies a positive pressure to the transfer head 50 to obtain the micro LED. Place (20) on the target substrate (60).

As described above, the micro LED 20 is adsorbed on the transfer head 50. The transfer head 50 positions the micro LED 20 as the target substrate 60. At this time, the transfer head 50 adsorbs the upper surface on which the non-electrode surface of the micro LED 20 loaded on the loading substrate 40 is positioned as described above, so that the electrode part 21 of the micro LED 20 is placed on the lower side. Transfer to a position.

The target substrate 60 may be implemented as a glass or flexible substrate, but the embodiment is not limited thereto. In addition, the target substrate 60 is a TFT array substrate, in which a plurality of pixel regions P are formed, and thin film transistors and wires for driving the micro LEDs 20 disposed in the pixel region P may be formed. .

In the arrangement step (S30), the transfer head 50 positions the electrode portion 21 of the micro LED 20 on the terminal portion 61 of the target substrate 60. Here, the terminal portion 61 of the target substrate 60 is electrically connected to the electrode portion 21 of the micro LED 20.

In this case, an electrically conductive ink may be applied to the terminal portion 61 of the target substrate 60. The electroconductive ink may bond the electrode portion 21 of the micro LED 20 and the terminal portion 61 of the target substrate 60.

In addition, the electroconductive ink can electrically connect the electrode portion 21 and the terminal portion 61. The electrically conductive ink according to an embodiment of the present invention may be implemented with an epoxy resin to which silver particles are added. In addition, the electrically conductive ink may be implemented with a viscous resin to which silver particles are added, but embodiments are not limited thereto. When the medium of the electroconductive ink is formed of an epoxy resin, the epoxy resin is a thermosetting resin and is cured after drying to have a large adhesive strength.

In addition, the electroconductive ink can re-contact the terminal portion 61 with the electrode portion 21 before drying. At this time, before drying of the electroconductive ink, the defective micro LED 20 is removed from the target substrate 60, and the normal micro LED 20 can be mounted on the target substrate 60.

That is, by inspecting the micro LED display 1, the micro LED 20 in the pixel area P in which the defective pixels are generated is removed from the target substrate 60, and a normal micro LED 20 can be mounted thereon. . Accordingly, it is possible to reduce the process cost for the final product and reduce the defect rate.

When the electrode portion 21 of the micro LED 20 is positioned on the terminal portion 61 of the target substrate 60 in the arrangement step S30, a positive pressure is applied to the transfer head 50.

That is, the micro LED 20 is formed in a micro size, as described above, and may be affected by a van der waals force. That is, in the case of the micro LED 20, the mass is very small due to the micro size, so that it can be attached to a specific object or maintain a contact state even with a small attraction. In particular, the larger the contact area with a specific object, the greater the Van der Waals force acting between the micro LEDs 20 may act.

In this case, van der Waals force may also act between the transfer head 50 and the micro LED 20. At this time, only by releasing the negative pressure on the transfer head 50, the micro LED 20 is not separated from the transfer head 50 and the adsorption state can be maintained.

Therefore, by applying a positive pressure to the transfer head 50, the micro LED 20 is separated from the transfer head 50. Accordingly, the micro LED 20 can be disposed on the target substrate 60.

In this case, since the transfer head 50 applies positive pressure when placing the micro LEDs 20 on the target substrate 60, it does not give an electric shock to the micro LEDs 20, thereby improving the transfer quality of the micro LEDs. Improve.

As described above, according to the micro LED transfer method of the present invention, the micro LED 20 can be quickly, accurately and stably transferred to the target substrate 60.

Meanwhile, referring to FIG. 8, the gripper 539 according to an embodiment of the present invention is formed to protrude from the transfer head body 531.

As described above, the micro LED 20 is formed in a micro size as described above, and may be affected by van der waals force. In this case, the micro LED 20 may not be easily separated from the transfer head 50 in the arrangement step S30.

In this case, in order to reduce the Van der Waals force, the gripper 539 of the present invention is formed to protrude from the transfer head body 531, so that the micro LED 20 is maximally separated from the transfer head body 531. Accordingly, the van der Waals force that can act on the micro LED 20 from the transfer head body 531 is reduced.

The gripper 539 may be formed in a cylindrical shape in which a second through hole 533 is formed, as shown in FIG. 8A. In addition, the gripper 539 may be formed in a square mold instead of a cylindrical shape, but the embodiment is not limited thereto.

The gripper 539 may have an inclined surface formed on the outer circumferential surface, as shown in FIG. 8B. That is, as described above, the van der Waals force may be applied to the micro LED 20, and the van der Waals force may increase as the area of the end of the gripper 539 in contact with the micro LED 20 increases. .

To solve this, an inclined surface is formed on the outer circumferential surface 539a of the gripper 539 to reduce the area of the end portion 539b of the gripper 539. Accordingly, the van der Waals force acting on the end portion 539b of the gripper 539 can be reduced.

Depending on the embodiment, a PDMS coating film may be formed on the end 539b of the gripper 539 in contact with the micro LED 20. When the PDMS coating film adsorbs the micro LED 20 to the gripper 539 in the pickup step S20, the adsorption force of the micro LED 20 and the gripper 539 may be increased. In addition, the PDMS coating film seals between the micro LED 20 and the end portion 539b of the gripper 539 so that the micro LED 20 can be stably adsorbed onto the gripper 539.

As described above, the target substrate 60 may be implemented as a glass or flexible substrate, but the embodiment is not limited thereto. In addition, the target substrate 60 is a TFT array substrate, in which a plurality of pixel regions P are formed, and thin film transistors and wires for driving the micro LEDs 20 disposed in the pixel region P may be formed. .

When the thin film transistor is turned on, a driving signal input from the outside through wiring is applied to the micro LED 20 so that the micro LED 20 emits light, thereby implementing an image.

At this time, since three micro LEDs 20 that emit monochromatic light of R, G, and B are mounted in each pixel area P of the target substrate 60, the R, G, and B colors are applied by applying a signal from the outside. Light is emitted so that an image can be displayed.

As described above, those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects.

The scope of the present invention is indicated by the scope of the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. It must be interpreted.

The present invention relates to a micro LED manufacturing method, a micro LED manufacturing apparatus, a manufacturing method and a manufacturing apparatus thereof, and can be used in various technical fields such as a micro LED display.

Claims

Micro LED preparation step of preparing a loading substrate on which the micro LED is loaded;

A pickup step of adsorbing the upper surface of the micro LED loaded on the loading substrate with a transfer head and separating the micro LED from the loading substrate; And

An arrangement step of placing the micro LED on the target substrate by placing the electrode portion of the micro LED into a terminal portion of the target substrate by the transfer head and applying a positive pressure to the transfer head; Including,

Micro LED transfer method of the elastic modulus of the transfer head is 0.00036 ~ 5.5 GPa.
The method of claim 1,

The step of preparing the micro LED,

A preparation step of disposing a plurality of micro LEDs positioned on the upper surface of the electrode unit to be spaced apart from each other on a separation substrate; And

A loading step of inverting the separation substrate to load the micro LED so that the electrode portion faces the loading substrate, and separating the micro LED from the separation substrate;

Micro LED transfer method comprising a.
The method of claim 2,

The preparation step,

A diode forming step of forming a diode by laminating an n layer, a light emitting layer, and a p layer on a growth substrate;

A separating substrate laminating step of laminating the separating substrate on the p-layer;

A growth substrate separation step of separating the growth substrate from the diode and inverting the separation substrate; And

Micro LED processing step of processing the diode into a micro LED;

Micro LED transfer method comprising a.
The method of claim 2,

The separation substrate is a thermal peeling tape or a UV peeling tape micro LED transfer method.
The method of claim 1,

The loading substrate is a micro LED transfer method of a PDMS film or an elastomer film.
The method of claim 1,

The loading substrate is any one of a polymer tape, a glass substrate, a polymer coated glass substrate, a SiC substrate, a GaAs substrate, a Si substrate, or a sapphire substrate.
The method of claim 2,

The loading step,

A micro LED arranging step in which the electrode portion of the micro LED is in contact with the loading substrate; And

A micro LED separating step of separating the micro LED from the separating substrate by applying heat or UV to the separating substrate;

Micro LED transfer method comprising a.
The method of claim 2,

The loading substrate,

A stacking die having a plurality of receiving grooves for accommodating one micro LED chip and having a first chamber formed therein;

A first through hole formed in the receiving groove and communicating with the first chamber; And

A vacuum module for applying a negative pressure to the first chamber;

Micro LED transfer method comprising a.
The method of claim 8,

The loading step,

A micro LED arranging step of arranging the electrode part of the micro LED to be seated in the receiving groove of the loading die; And

A micro LED separating step of separating the micro LED from the separating substrate by applying a negative pressure to the first chamber to fix the micro LED in the receiving groove and then applying heat or UV to the separating substrate;

Micro LED transfer method comprising a.
The method of claim 1,

The transfer head,

A transfer head body having a second chamber formed therein;

A gripper provided to protrude from the transfer head body to contact the micro LED;

A second through hole formed to pass through the gripper and communicating with the second chamber; And

A pressure applying module for applying a negative or positive pressure to the second chamber;

Micro LED transfer method comprising a.
The method of claim 10,

In the pickup step, a micro LED transfer method of applying a negative pressure to the second chamber to adsorb the micro LED with the gripper.
The method of claim 10,

The transfer head is a micro LED transfer method in which one of the plurality of micro LEDs loaded on the loading substrate is adsorbed, and other micro LEDs adjacent to the adsorbed micro LEDs are placed on the loading substrate.
The method of claim 8,

The loading step includes a micro LED separating step of separating the micro LED from the separating substrate by applying a negative pressure to the first chamber to fix the micro LED in the receiving groove and then applying heat or UV to the separating substrate. Micro LED transfer method.
The method of claim 13,

In the pickup step, the absolute value of the sound pressure applied to the second chamber is applied to a value greater than the absolute value of the sound pressure applied to the first chamber.
The method of claim 1,

Micro LED transfer method in which an electrically conductive ink is applied to the terminal portion of the target substrate.
The method of claim 10,

The gripper is a micro LED transfer method in which an inclined surface is formed on an outer circumferential surface.
The method of claim 1,

The transfer head is a micro LED transfer method made of at least one of polycarbonate, polyurethane, urethane acrylate, isobornyl acrylate, epoxy, or PDMS.
A micro LED display manufactured by the method of any one of claims 1 to 17.