KR102364729B1 - Method of transferring micro light emitting device - Google Patents

Abstract

The embodiment includes the steps of transferring a plurality of micro light emitting devices formed on a first substrate to a first adhesive member; transferring the plurality of micro light emitting devices from the first adhesive member to a second adhesive member; and transferring the plurality of micro light emitting devices from the second adhesive member to a second substrate, wherein in the transferring to the first adhesive member, a first temperature for controlling the first adhesive member is the second The second temperature is different from the second temperature for controlling the first and second adhesive members in the step of transferring to the adhesive member, and the second temperature is different from the second temperature in the step of transferring to the second substrate. The second temperature is different from the third temperature for controlling the conductive adhesive layer of the substrate, and the first temperature and the third temperature are higher than the second temperature.

Description

Micro light emitting device transfer method {METHOD OF TRANSFERRING MICRO LIGHT EMITTING DEVICE}

The embodiment relates to a method for transferring a micro light emitting device.

Recently, in the field of display technology, a display device having excellent characteristics such as thinness and flexibility has been developed. In contrast, currently commercialized major displays are represented by liquid crystal displays (LCDs) and organic light emitting diodes (OLEDs).

Although the development of OLED displays is active in recent years, OLED displays have short lifespan and poor mass production yield.

A light emitting diode (LED) is one of light emitting devices that emits light when an electric current is applied thereto. Light-emitting diodes can emit high-efficiency light with low voltage, and thus have an excellent energy-saving effect. Recently, the luminance problem of light emitting diodes has been greatly improved, and it has been applied to various devices such as a backlight unit of a liquid crystal display device, an electric sign board, a display device, and a home appliance.

A light emitting diode including a compound such as GaN or AlGaN has many advantages, such as having a wide and easily adjustable band gap energy, and thus can be used in various ways as a light emitting device, a light receiving device, and various diodes. In particular, it has advantages of low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness.

Recently, research on a technology for using a micro light emitting diode made of a small light emitting diode as a pixel of a display is being conducted. Since these micro light emitting devices are very small, it is important to transfer them to another substrate in a large area.

Conventionally, there is a problem in that it is difficult to transfer a large area because a laser is irradiated and separated from a micro light emitting device manufactured on a substrate, and there is a problem in that secondary transfer or selective transfer is difficult. Also, there is a problem that repair is impossible.

Embodiments may provide a transfer method that facilitates transfer of a large area.

In the embodiment, it may be possible to transfer (flip) several times using the difference in adhesive force.

Embodiments may provide a transfer method capable of selective transfer.

The problem to be solved in the embodiment is not limited thereto, and it will be said that the purpose or effect that can be grasped from the method of solving the problem described below or the embodiment is also included.

According to one aspect of the present invention, there is provided a method for transferring a micro light emitting device, comprising: transferring a plurality of micro light emitting devices formed on a first substrate to a first adhesive member; transferring the plurality of micro light emitting devices from the first adhesive member to a second adhesive member; and transferring the plurality of micro light emitting devices from the second adhesive member to a second substrate, wherein in the transferring to the first adhesive member, a first temperature for controlling the first adhesive member is the second The second temperature is different from the second temperature for controlling the first and second adhesive members in the step of transferring to the adhesive member, and the second temperature is different from the second temperature in the step of transferring to the second substrate. 2 is different from a third temperature for controlling the conductive adhesive layer of the substrate, wherein the first temperature and the third temperature are higher than the second temperature.

According to the embodiment, it may be possible to transfer a large area of the micro light emitting device.

An embodiment may enable selective transfer of the micro light emitting device.

Various and advantageous advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

1 is a flowchart of a method for transferring a micro light emitting device according to an embodiment of the present invention;
2 is a view showing a state in which a light emitting structure is grown on a first substrate;
3 is a view showing a state in which a micro light emitting device is fabricated on a first substrate;
4 is a view showing a state in which a plurality of protrusions are formed by etching the upper surface of the first substrate;
5 is a partially enlarged view of FIG. 4;
Figure 6 is a modified example of Figure 5,
7 and 8 are views showing a state in which a first adhesive member is attached to one surface of a plurality of micro light emitting devices;
9A is a view showing a state in which a plurality of micro light emitting devices are transferred to the first adhesive member by separating the first adhesive member and the first substrate;
9B is a view for explaining a direction in which a plurality of micro light emitting devices are separated from a first substrate;
Figure 9c is a modification of Figure 9b,
Figure 10 is a modified example of Figure 9a,
11 is a plan view showing a plurality of micro light emitting devices transferred to the first adhesive member;
12 is a view showing a state in which the micro light emitting device is transferred to the first adhesive member;
13 and 14 are views showing a state in which a second adhesive member is attached to the other surfaces of a plurality of micro light emitting devices;
15A is a side view illustrating a state in which a plurality of micro light emitting devices are transferred to a second adhesive member by separating the second adhesive member and the first adhesive member;
Figure 15b is a first modification of Figure 15a,
Figure 15c is a second modification of Figure 15a,
15D is a third modified example of FIG. 15A,
16 and 17 are views showing a state in which one surface of a plurality of micro light emitting devices is attached on a second substrate;
18A is a side view illustrating a state in which a plurality of micro light emitting devices are transferred to a second substrate by separating the second adhesive member from the second substrate;
Figure 18b is a first modification of Figure 18a,
Figure 18c is a second modification of Figure 18a,
18D is a third modified example of FIG. 18A,
19 is a view showing a state in which a plurality of micro light emitting devices are electrically connected to a second substrate using a pressing member;
20 is a view showing a state in which a micro light emitting device is electrically connected to an electrode of a second substrate;
21 is a conceptual diagram of a display device to which a micro light emitting device is transferred according to an embodiment of the present invention.

Since the present invention may have various changes and may have various embodiments, specific embodiments will be illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms including an ordinal number such as second, first, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as the first component, and similarly, the first component may also be referred to as the second component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, the embodiment will be described in detail with reference to the accompanying drawings, but the same or corresponding components are given the same reference numerals regardless of reference numerals, and overlapping descriptions thereof will be omitted.

The micro light emitting device may be a light emitting diode having a size of 1 μm to 200 μm. Illustratively, the size of the micro light emitting device may be 30 μm to 60 μm, but is not limited thereto, and light emitting devices of various sizes may be used. In addition, a mini-size light emitting device of 200 μm to 500 μm may be applied in addition to the micro light emitting device.

A display device according to an embodiment of the present invention includes SD (Standard Definition) level resolution (760×480), HD (High Definition) level resolution (1180×720), FHD (Full HD) level resolution (1920×1080), UH (Ultra HD) level resolution (3480×2160), or UHD level or higher resolution (eg, 4K (K=1000), 8K, etc.) may be implemented. In this case, a plurality of micro light emitting devices according to the embodiment may be arranged and connected to suit the resolution.

1 is a flowchart of a method for transferring a micro light emitting device according to an embodiment of the present invention.

Referring to FIG. 1 , the micro light emitting device transfer method according to the embodiment includes the steps of transferring a plurality of micro light emitting devices disposed on a first substrate to a first adhesive member (S20), and transferring the plurality of micro light emitting devices to a first adhesive member and transferring the plurality of micro light emitting devices from the second adhesive member to the second substrate (S40).

In addition, the micro light emitting device transfer method according to the embodiment may further include manufacturing the micro light emitting device on the first substrate ( S10 ) and electrically connecting the micro light emitting device to the second substrate ( S50 ).

Each step will be described in detail below.

FIG. 2 is a view showing a state in which a light emitting structure is grown on a first substrate, FIG. 3 is a view showing a state in which a micro light emitting device is manufactured on a first substrate, and FIG. It is a view showing a state in which the protrusion is formed, FIG. 5 is a partially enlarged view of FIG. 4 , and FIG. 6 is a modified example of FIG. 5 .

Referring to FIG. 2 , in the step of fabricating the micro light emitting device on the first substrate 110 ( S10 ), the light emitting structure 120 may be formed on the first substrate 110 . The first substrate 110 may be a silicon (Si) substrate, but is not limited thereto, and substrates of various materials may be applied without limitation.

The light emitting structure 120 may be formed by a metal organic chemical vapor deposition (MOCVD) method, a chemical vapor deposition method (CVD), a plasma-enhanced chemical vapor deposition (PECVD) method, or a molecular beam growth method (Molecular Beam). Epitaxy; MBE), hydride vapor phase epitaxy (HVPE), sputtering (Sputtering), etc. may be used for epitaxial growth.

Referring to FIG. 3 , after the light emitting structure 120 is separated into a plurality of pieces, a first electrode 131 and a second electrode 132 are respectively formed to manufacture a plurality of micro light emitting devices.

3 and 4 , the upper surface 110a of the first substrate 110 may be etched to form a plurality of protrusions 111 connected to the plurality of micro light emitting devices. The plurality of protrusions 111 may be formed by etching the upper surface 110a of the first substrate by contacting the etching solution. As the etching solution, a solution that does not damage the micro light emitting device while etching the silicon substrate may be used without limitation. Illustratively, the etching solution may be selected from HCl, HF, BOE, HNA (HF, HNO _3, CH ₃ COOH), KOH, TMAH (Tetramethyl Ammonium Hydroxide), EDP (Ethylene Diamine Pyrochatechol), etc., but is not necessarily limited thereto. .

Referring to FIG. 5 , the width of the protrusion 111 may be smaller than the width of the micro light emitting device 10A. Specifically, the width of the protrusion 111 may be 0.01 to 0.3 times the width of the micro light emitting device 10A. When the width of the protrusion 111 is less than 0.01 times, the width of the protrusion 111 becomes too thin to support and fix the micro light emitting device. When the width of the protrusion 111 is greater than 0.3 times, the width of the protrusion 111 is too large It may become thick and difficult to transfer. For example, when the size of the micro light emitting device is smaller than 100 μm, the width of the protrusion 111 may be smaller than 0.1 times the short side surface of the micro light emitting device.

The light emitting structure 120 may include a first conductivity type semiconductor layer 121 , an active layer 122 , and a second conductivity type semiconductor layer 123 . The light emitting structure 120 may have a structure in which a first conductivity type semiconductor layer 121 , an active layer 122 , and a second conductivity type semiconductor layer 123 are sequentially stacked.

The first conductivity type semiconductor layer 121 may be implemented with a group III-V group or group II-VI compound semiconductor, and the first conductivity type semiconductor layer 121 may be doped with a first dopant. The first conductivity type semiconductor layer 121 is a semiconductor material having a composition formula of AlxInyGa(1-xy)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1), InAlGaN, AlGaAs, GaP , GaAs, GaAsP, may be formed of any one or more of AlGaInP, but is not limited thereto. When the first dopant is an n-type dopant such as Si, Ge, Sn, Se, or Te, the first conductivity-type semiconductor layer 121 may be an n-type nitride semiconductor layer.

The active layer 122 may be disposed on the first conductivity-type semiconductor layer 121 . Also, the active layer 122 may be disposed between the first conductivity-type semiconductor layer 121 and the second conductivity-type semiconductor layer 123 .

The active layer 122 is a layer in which electrons (or holes) injected through the first conductivity type semiconductor layer 121 and holes (or electrons) injected through the second conductivity type semiconductor layer 123 meet. The active layer 122 may transition to a low energy level as electrons and holes recombine, and may generate light having a corresponding wavelength.

The active layer 122 may have any one of a single well structure, a multi-well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, or a quantum wire structure, and the active layer 122 . The structure of is not limited thereto. The active layer may generate light in a wavelength band of visible light.

Exemplarily, the active layer may output light in any one wavelength band of blue, green, and red. However, the present invention is not limited thereto, and the active layer 122 may generate light in an ultraviolet wavelength band or light in an infrared wavelength band.

The second conductivity type semiconductor layer 123 may be disposed on the active layer 122 . The second conductivity-type semiconductor layer 123 may be implemented with a group III-V or group II-VI compound semiconductor, and the second conductivity-type semiconductor layer 123 may be doped with a second dopant.

The second conductivity type semiconductor layer 123 is a semiconductor material having a composition formula of Inx5Aly2Ga1-x5-y2N (0≤x5≤1, 0≤y2≤1, 0≤x5+y2≤1) or AlInN, AlGaAs, GaP, GaAs , GaAsP, may be formed of a material selected from AlGaInP. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, or Ba, the second conductivity-type semiconductor layer 123 doped with the second dopant may be a p-type semiconductor layer. A reflective layer 150 may be formed on the second conductivity-type semiconductor layer 123 . The reflective layer 150 is not particularly limited as long as it is a material capable of reflecting the light emitted to the active layer 122 . For example, the reflective layer 150 may include at least one of Ag, Au, Ni, Ti, and Al.

The first electrode 131 may be disposed on the first conductivity-type semiconductor layer 121 . Here, a portion of the first conductivity type semiconductor layer 121 may be exposed by etching. In addition, the first electrode 131 may be disposed on the first conductivity-type semiconductor layer 121 exposed by etching.

The first electrode 131 includes the 1-1 electrode 131a disposed on the first conductivity-type semiconductor layer 121 and the 1-2 electrode 131b formed on the 1-1 electrode 131a. may include The first-first electrode 131a may be formed to compensate for the height at which the first conductivity-type semiconductor layer 121 is etched. The material of the first-first electrode 131a and the first-second electrode 131b may be the same.

The second electrode 132 may be disposed on the second conductivity-type semiconductor layer 123 . The second electrode 132 may be electrically connected to the second conductivity-type semiconductor layer 123 .

The first electrode 131 and the second electrode 132 may include at least one of Cr, Au, Ni, Ti, TiN, AuGe, AuNi, and Al, but is not limited thereto.

The thicknesses d1 and d2 of the first electrode 131 and the second electrode 132 may be 3 μm or more. When the thickness of the first electrode 131 and the second electrode 132 is 3 μm or more, even if the conductive ball is inserted between the first electrode 131 and the second electrode 132 , it is not pressed, so that an electric channel is not formed. . Therefore, short circuit can be prevented.

The insulating layer 141 may be disposed on the upper surface of the light emitting structure 120 . However, the present invention is not limited thereto, and the insulating layer may be formed to extend to the side surface of the light emitting structure 120 .

The insulating layer 141 may include at least one of SiO ₂ , Si _x O _y , Si ₃ N ₄ , Si _x N _y , SiO _x N _y , Al ₂ O ₃ , TiO ₂ , AlN, and HfxOy, but must be It is not limited to this.

Referring to FIG. 6 , the micro light emitting device 10B according to the embodiment may be manufactured in a flip-chip type. The first electrode 131 may pass through the second conductivity type semiconductor layer 123 and the active layer 122 to be electrically connected to the first conductivity type semiconductor layer 121 .

7 and 8 are views illustrating a state in which a first adhesive member is attached to one surface of a plurality of micro light emitting devices, and FIG. 9A is a first adhesive member and a first substrate spaced apart to emit a plurality of micro light on the first adhesive member It is a view showing a state in which a device is transferred, FIG. 9B is a view for explaining a direction in which a plurality of micro light emitting devices are separated from a first substrate, and FIG. 9C is a modified example of FIG. 9B .

The transferring to the first adhesive member (S20) includes disposing the first adhesive member 200 on one surface (S1) of the plurality of micro light emitting devices, and disposing the plurality of micro light emitting devices on the first substrate 110 . Separation may be included.

Referring to FIG. 7 , in the step of disposing the first adhesive member 200, the central portion of the first adhesive member 200 is first attached to one surface S1 of the plurality of micro light emitting devices, and then, as shown in FIG. 1 It is preferable that the entire surface of the adhesive member 200 is attached to the plurality of micro light emitting devices 10 . According to this method, since bubbles are prevented from being formed between the first adhesive member 200 and the first substrate 110 , transfer efficiency can be increased.

The first adhesive member 200 may include a first base layer 220 and a first adhesive layer 210 disposed on the first base layer 220 . The thickness of the first adhesive layer 210 may be 15 μm or less. When the thickness of the first adhesive layer 210 is greater than 15 μm, the thickness of the first adhesive layer 210 is too thick, so that the chip is buried too deeply in the first adhesive layer 210 , and transfer may be difficult. That is, in addition to the GaN on Si micro LED chip, the Si substrate layer between the chip and the chip may also be attached to the surface layer of the Si substrate to be separated. In addition, when flipping the second adhesive member, the chip may be buried in the adhesive layer 210 of the first adhesive member, so that the entire first adhesive layer may be transferred to the second adhesive member.

In addition, during the transfer process, the first adhesive layer 210 itself may be transferred away from the first base layer 220 .

The first adhesive layer 210 may have an adhesive strength that can be used as an adhesive at 50° C. to 90° C., and may have a maximum adhesive strength within a first temperature of 50° C. to 70° C. The maximum adhesive force of the first adhesive layer may be 0.8N/25mm to 2.0N/25mm.

The first adhesive member 200 may include a temperature-variable adhesive layer. The first adhesive layer 210 is not particularly limited as long as it is a thermoplastic resin having a maximum adhesive strength within a temperature range of 50° C. to 70° C. and a low adhesive strength when out of the temperature.

When the first adhesive member 200 is attached to one surface S1 of the plurality of micro light emitting devices in a state in which the temperature is adjusted to 50 ° C to 70 ° C, the first adhesive member 200 is a plurality of micro light emitting devices 10 . can be strongly attached to

The first substrate 110 may be disposed on the first holder 1001 , and the first adhesive member 200 may be disposed on the second holder 1002 . The first holder 1001 may include a temperature control member (not shown) capable of cooling or heating the first substrate 110 , and the second holder 1002 may heat the first adhesive member 200 . It may be provided with a temperature control member (not shown) that can.

Accordingly, the first substrate 110 and the first adhesive member 200 may be maintained at a first temperature of 50° C. to 70° C. for a predetermined time. In this process, the first adhesive member 200 may be strongly coupled to the micro light emitting device. When the first substrate 110 is heated to the first temperature, the adhesive surface of the first adhesive layer 210 may be maintained at the first temperature, thereby increasing transfer efficiency.

The temperature control member may be a heater or a Peltier element, but is not necessarily limited thereto. However, the present invention is not necessarily limited thereto, and the first holder 1001 and/or the second holder 1002 may be omitted if necessary.

8 and 9A , in the step of separating the plurality of micro light emitting devices 10 from the first substrate 110 , the first adhesive member 200 is spaced apart from the first substrate 110 to form the micro light emitting devices. can fight

In this case, after reducing the temperature of the first adhesive member 200 to 70 to 80% of the first temperature, the separation operation may be performed. In this process, the adhesive force of the first adhesive member 200 may drop to 40% to 80% of the maximum adhesive force. When the first adhesive member 200 is separated in a state having the maximum adhesive force, in addition to the chip of the GaN on Si wafer, the surface of the Si wafer between the chip and the chip is separated together, so that only the micro LED chip is selectively separated from the first substrate 110 Because there are difficult problems. For example, when the temperature of the first adhesive member 200 is cooled to 35°C to 45°C, the adhesive force may be lowered to 0.6N/25mm to 0.8N/25mm.

The first adhesive member 200 may be cooled to about 35° C. to 45° C. by the second holder 1002 , but the control temperature is not necessarily limited thereto. That is, it can be separated from the first substrate 110 and adjusted to an appropriate temperature at which the micro light emitting device can be transferred.

As a method of cooling the first adhesive member 200 , the first holder 1001 and the second holder 1002 may be used. That is, the first substrate 110 is cooled to 35° C. to 45° C. using the first holder 1001 , and the first adhesive member 200 is cooled to 35° C. to 45° C. using the second holder 1002 . can do it However, the present invention is not necessarily limited thereto and may be naturally cooled.

Referring to FIG. 9A , when one side of the first substrate 110 is lifted while the first adhesive member 200 is fixed, the protrusions 111 connected to the plurality of micro light emitting devices 10 are separated and a plurality of micro light emitting devices are separated. The device may be transferred to the first adhesive member 200 . In this process, a portion of the protrusion 111 may remain in the micro light emitting device 10 . In this case, the first substrate 110 may be lifted by the first holder 1001 , but is not limited thereto.

Referring to FIG. 9B , the protrusion 111 may have a rectangular shape having a long side surface and a short side surface. In this case, the direction D1 of the force separating the plurality of micro light emitting devices 10 from the substrate may be a direction perpendicular to the long side surface. Accordingly, the protrusion 111 may be easily separated from the first substrate 110 . If the direction of the force to separate the plurality of micro light emitting devices from the substrate is parallel to the long side, more force may be applied to separate the micro light emitting devices, and thus transfer failure may occur. In addition, the micro light emitting device may be damaged by excessive force.

The shape of the protrusion 111 may have various shapes according to manufacturing conditions. Referring to FIG. 9C , the protrusion 111 may have a polygonal shape. When the shape of the protrusion 111 is hexagonal, the direction of the force separating the plurality of micro light emitting devices 10 from the substrate may be parallel to the short side surface of the micro light emitting device 10 .

Fig. 10 is a modification of Fig. 9A.

Referring to FIG. 10 , the transfer may be performed by lifting the first substrate 110 in a vertical direction to the first adhesive member 200 without tilting it. Since the temperature of the first substrate 110 and the first adhesive member 200 was adjusted to 35° C. to 45° C. by the first holder and the second holder, the adhesive force was lowered, so even when the first substrate 110 is separated without tilting it. The transfer efficiency can be high.

11 is a plan view showing a plurality of micro light emitting devices transferred to the first adhesive member, and FIG. 12 is a view showing a state in which the micro light emitting devices are transferred to the first adhesive member.

11 and 12 , according to the embodiment, after the protrusion 111 is formed on the first substrate 110, it is transferred using the first adhesive member 200, so that most of the micro light emitting devices 10 are transferred. can be Accordingly, large-area transfer is possible and transfer efficiency can be increased.

11 illustrates that all of the plurality of micro light emitting devices on the first substrate 110 are transferred to the first adhesive member 200, but the present invention is not limited thereto. By patterning the first adhesive member 200 , only some of the plurality of micro light emitting devices formed on the first substrate 110 may be selectively transferred.

13 and 14 are views illustrating a state in which a second adhesive member is attached to the other surfaces of a plurality of micro light emitting devices.

The transferring to the second adhesive member (S30) includes disposing the second adhesive member 300 on the other surface S2 of the plurality of micro light emitting devices, and attaching the plurality of micro light emitting devices to the first adhesive member 200 It may include the step of separating from

Referring to FIG. 13 , in the step of disposing the second adhesive member 300 on the other surface S2 of the plurality of micro light emitting devices, the central portion of the second adhesive member 300 is first the other surface S2 of the plurality of micro light emitting devices. ), it is preferable that the entire surface of the second adhesive member 300 is attached to the plurality of micro light emitting devices 10 as shown in FIG. 14 . In this case, it is possible to prevent air bubbles from being formed between the first adhesive member 200 and the second adhesive member 300 .

The second adhesive member 300 may include a second base layer 320 and a second adhesive layer 310 disposed on the second base layer 320. The thickness of the second adhesive member 300 is particularly not limited For example, the thickness of the second adhesive member 300 may be thicker than that of the first adhesive member.

The second adhesive layer 310 may be used at less than 50° C., and may have a maximum adhesive strength at a second temperature of 1° C. to 10° C. The maximum adhesive force of the second adhesive layer may be 0.8N/25mm to 2.0N/25mm. For example, the second adhesive member 300 may include a temperature-variable adhesive layer. The second adhesive layer 310 is not particularly limited as long as the adhesive force is maximized at a temperature of 1° C. to 10° C. and is a thermoplastic resin in which the adhesive force decreases as it goes out of this range.

The second adhesive member 300 may be disposed on the third holder 1004 . The third holder 1004 may include a temperature control member (not shown) capable of cooling or heating the second adhesive member 300 . The temperature control member may be a heater or a Peltier element, but is not necessarily limited thereto.

15A is a side view illustrating a state in which a plurality of micro light emitting devices are transferred to a second adhesive member by separating the second adhesive member from the first adhesive member, and FIG. 2 It is a plan view showing a state in which a plurality of micro light emitting devices are transferred to an adhesive member, and FIG. 15C is a modification of FIG. 15A .

Referring to FIG. 15A , the step of separating the plurality of micro light emitting devices from the first adhesive member 200 includes heating the first adhesive member 200 and the second adhesive member 300 at a second temperature of 1°C to 10°C. After cooling, it can be maintained for a certain period of time. In this process, the second adhesive member 300 may be strongly coupled to the micro light emitting device 10 by increasing adhesive force. Conversely, the adhesive force of the first adhesive member 200 is gradually lowered as the temperature decreases, and the adhesive force may be minimized at a temperature of 1°C to 10°C. That is, at the second temperature of 1° C. to 10° C., the adhesive force of the second adhesive member 300 may be greater than that of the first adhesive member 200 .

According to the embodiment, since the first adhesive member 200 is cooled by the second holder 1002 and the second adhesive member 200 is cooled by the third holder 1004, the adhesive surface of the first adhesive layer 210 is The adhesive surface of the and the second adhesive layer 310 may be precisely controlled to the second temperature.

Thereafter, when the second adhesive member 300 and the first adhesive member 200 are spaced apart, the plurality of micro light emitting devices 10 may be transferred to the second adhesive member 300 .

While the second adhesive member 300 is fixed to the holder, the first adhesive member 200 may be lifted for transfer, but the present invention is not limited thereto. Illustratively, the transfer may be performed by lifting the second adhesive member while the first adhesive member is fixed to the holder.

15B, the first adhesive member 200 includes a first side 201 and a second side 202 facing each other, and a third side 203 and a fourth side 204 facing each other, , may be peeled off by lifting one edge 207 of the first adhesive member 200 . Alternatively, it may be peeled off by lifting the second side surface 202 as shown in FIG. 15C . Alternatively, as shown in FIG. 15D , the first adhesive member 200 and the second adhesive member 300 may be peeled off by lifting them in a vertical direction in a state in which they face each other in parallel.

16 and 17 are views illustrating a state in which one surface of a plurality of micro light emitting devices is attached on a second substrate.

The step of transferring (S40) from the second adhesive member to the second substrate includes attaching one surface S1 of the plurality of micro light emitting devices to the second substrate 400, and attaching the plurality of micro light emitting devices to the second adhesive member. It may include the step of separating in (300).

16 and 17 , the step of disposing one surface S1 of the plurality of micro light emitting devices on the second substrate 400 is performed by first maintaining the temperature of the second adhesive member 300 at room temperature. can do. If the temperature of the second adhesive member 300 is maintained at the second temperature, since the second adhesive layer 310 is too soft, the plurality of micro light emitting devices 10 are formed when pressed with the second substrate 400 . This is because it may be deeply buried with the second adhesive layer 310 by being pushed to the second substrate 400 before being attached to the substrate 400 . Accordingly, the third holder 1004 may be heated so that the temperature of the second adhesive member 300 is at room temperature (fourth temperature) of 10°C to 30°C. Alternatively, the temperature may be raised to room temperature by allowing it to stand for a predetermined time. In this process, the adhesive force of the second adhesive member may drop to 40% to 70% of the maximum adhesive force. In this case, the fourth holder 1003 may previously heat the conductive adhesive layer 500 of the second substrate 400 to a third temperature.

Thereafter, in the step of disposing one surface S1 of the plurality of micro light emitting devices on the second substrate 400, one surface S1 of the plurality of micro light emitting devices faces the second substrate 400 on which the conductive adhesive layer 500 is formed. After disposing to be viewed, the second adhesive member 300 may be pressed to the second substrate 400 at 1 kgf to 2 kgf to attach the plurality of micro light emitting devices to the conductive adhesive layer 500 of the second substrate 400 . The second substrate 400 may be a display substrate. A circuit for driving a pixel may be formed on the second substrate 400 .

The second substrate 400 may be disposed on the fourth holder 1003 , and the second adhesive member 300 may be in contact with the third holder 1004 . In this case, the fourth holder 1003 may include a temperature control member (not shown) capable of cooling or heating the second substrate 400 . The temperature control member may be a heater or a Peltier element, but is not necessarily limited thereto.

18A is a side view illustrating a state in which a plurality of micro light emitting devices are transferred to a second substrate by separating the second adhesive member from the second substrate, and FIG. 18B is a second adhesive member and a second substrate spaced apart from the second substrate It is a plan view showing a state in which a plurality of micro light emitting devices are transferred, and FIG. 18C is a modified example of FIG. 18A .

Referring to FIG. 18A , in the step of separating the second adhesive member 300 from the plurality of micro light emitting devices, the second substrate 400 and the second adhesive by using the third holder 1004 and the fourth holder 1003 . The member 300 may be heated.

The adhesive force of the second adhesive member 300 is gradually weakened as the temperature increases, and the adhesive force may be minimized at a third temperature of 70°C to 80°C. As a result, the adhesive force of the conductive adhesive layer 500 at the third temperature may be greater than that of the second adhesive member 300 . That is, the third temperature may be higher than the first temperature.

Accordingly, when the second adhesive member 300 is separated from the second substrate 400 in a state in which the second adhesive member 300 is heated to 70° C. to 80° C., the plurality of micro light emitting devices 10 are formed on the second substrate ( 400) can be transcribed.

While the second substrate 400 is fixed to the holder, the second adhesive member 300 may be lifted and transferred, but the present invention is not limited thereto. For example, the second substrate may be lifted and transferred while the second adhesive member is fixed to the holder.

Referring to FIG. 18B , the second adhesive member 300 includes a first side surface 301 and a second side surface 302 facing each other, and a third side surface 303 and a fourth side surface 304 facing each other, , may be peeled off by lifting one edge 307 of the second adhesive member 300 . Alternatively, it may be peeled off by lifting the second side surface 302 as shown in FIG. 18C . Alternatively, as shown in FIG. 18D , the second adhesive member 300 and the second substrate 400 may be peeled off by lifting them in a vertical direction while facing each other in parallel.

Electrical connection between the plurality of micro light emitting devices and the second substrate may be performed collectively after the transfer of all the micro light emitting devices is completed. Illustratively, when transferring a micro light emitting device of a 2 inch, 4 inch, or 6 inch substrate to a large panel, it is essential to perform the above-described transfer process several times. Accordingly, after repeating the above-described steps to transfer the number of micro light emitting devices suitable for resolution to the display substrate, the electrical connection process and bonding operation may be performed.

In addition, after transferring the micro light emitting device emitting blue light to the second substrate 400 to configure the RGB pixel, the micro light emitting device emitting green light and red light may be sequentially transferred to the second substrate 400 again. . Thereafter, the RGB micro light emitting device may be bonded to the second substrate 400 at once. In this case, the first adhesive member may be patterned so that only necessary micro light emitting devices can be transferred.

19 is a view showing a state in which a plurality of micro light emitting devices are electrically connected to a second substrate using a pressing member, and FIG. 20 is a view showing a state in which the micro light emitting devices are electrically connected to a circuit electrode of the second substrate .

Referring to FIG. 19 , when the transfer of all the micro light emitting devices is completed, the plurality of micro light emitting devices 10 may be pressed using the pressing member 600 . Exemplarily, heat of 300° C. to 350° C. and pressure of 8 kgf to 12 kgf may be applied.

Referring to FIG. 20 , the conductive adhesive layer 500 may be an anisotropic conductive film (ACF). Accordingly, when the micro light emitting device is pressed, the conductive balls 500a dispersed in the conductive adhesive layer 500 of the second substrate 400 are pressed together to form an electrical path. When pressurizing, the resin layer surrounding the conductive ball 500a is removed, and cracks are generated in the conductive ball 500a, thereby forming an electrical path. When heat of 300° C. to 350° C. is applied, curing of the conductive adhesive layer 500 may be completed.

That is, in the step of temporary bonding a plurality of micro light emitting devices as shown in FIG. 17, heat of 50° C. to 70° C. and pressure of 1 kgf to 2 kgf/cm2 are applied, so that the conductive adhesive layer 500 is not cured and the conductive ball passes through an electrical passage. does not form

However, in the bonding step, since heat of 300° C. to 350° C. and pressure of 8 kgf to 12 kgf/cm 2 are applied, the conductive adhesive layer 500 is cured and the conductive balls form an electrical passage.

In this case, the thicknesses d1 and d2 of the first and second electrodes 131 and 132 of the micro light emitting device 10 may be equal to or greater than the diameter d3 of the conductive ball 500a. If the thickness of the electrode of the micro light emitting device 10 is smaller than the conductive ball 500a, the conductive ball 500a positioned between the first electrode 131 and the second electrode 132 forms an electrical path by pressure. This may cause a short circuit. In addition, the end face of the first electrode 131 and the end face of the second electrode 132 are manufactured to have the same height, so that they may have the same height despite the step difference of the light emitting structure.

The thickness of the conductive adhesive layer 500 may be 15 μm or less. If the thickness of the conductive adhesive layer is greater than 15 μm, the micro light emitting device having a thickness of about 5 μm may be broken.

21 is a conceptual diagram of a display device to which a micro light emitting device is transferred according to an embodiment of the present invention.

Referring to FIG. 21 , a display device including a micro light emitting device includes a second panel substrate 410 , a driving thin film transistor T2 , a planarization layer 430 , a common electrode CE, a pixel electrode AE, and a micro light emitting device. It may include elements.

The driving thin film transistor T2 may include a gate electrode GE, a semiconductor layer SCL, an ohmic contact layer OCL, a source electrode SE, and a drain electrode DE.

The driving thin film transistor is a driving device and may be electrically connected to the micro light emitting device to drive the micro light emitting device.

The gate electrode GE may be formed together with the gate line. The gate electrode GE may be covered with a gate insulating layer 440 .

The gate insulating layer 440 may be formed of a single layer or a plurality of layers made of an inorganic material, and may be made of silicon oxide (SiOx), silicon nitride (SiNx), or the like.

The semiconductor layer SCL may be disposed in the form of a preset pattern (or island) on the gate insulating layer 440 to overlap the gate electrode GE. The semiconductor layer SCL may be made of a semiconductor material made of any one of amorphous silicon, polycrystalline silicon, oxide, and an organic material, but is not limited thereto.

The ohmic contact layer OCL may be disposed in a preset pattern (or island) shape on the semiconductor layer SCL. The ohmic contact layer PCL may be for ohmic contact between the semiconductor layer SCL and the source/drain electrodes SE and DE.

The source electrode SE is formed on the other side of the ohmic contact layer OCL to overlap one side of the semiconductor layer SCL.

The drain electrode DE may be formed on the other side of the ohmic contact layer OCL to be spaced apart from the source electrode SE while overlapping the other side of the semiconductor layer SCL. The drain electrode DE may be formed together with the source electrode SE.

The planarization layer may be disposed over the entire surface of the second panel substrate 410 . A driving thin film transistor T2 may be disposed inside the planarization layer. The planarization layer according to an embodiment may include an organic material such as benzocyclobutene or photo acryl, but is not limited thereto.

In the micro light emitting device, first and second electrodes may be connected to a circuit (not shown) of the display device. The second electrode 132 of the micro light emitting device may be electrically connected to the source electrode SE of the driving thin film transistor T2 through the pixel electrode AE. In addition, the first electrode 131 of the micro light emitting device may be connected to the common power line CL through the common electrode CE. In this case, a portion of the protrusion 111a may remain on the upper surface of the micro light emitting device.

The pixel electrode AE may electrically connect the source electrode SE of the driving thin film transistor T2 and the second electrode of the micro light emitting device.

The common electrode CE may electrically connect the common power line CL and the first electrode of the micro light emitting device.

Each of the pixel electrode AE and the common electrode CE may include a transparent conductive material. The transparent conductive material may include a material such as indium tin oxide (ITO) or indium zinc oxide (IZO), but is not limited thereto.

A display device according to an embodiment of the present invention includes SD (Standard Definition) level resolution (760×480), HD (High Definition) level resolution (1180×720), FHD (Full HD) level resolution (1920×1080), UH (Ultra HD) level resolution (3480×2160), or UHD level or higher resolution (eg, 4K (K=1000), 8K, etc.) may be implemented. In this case, a plurality of micro light emitting devices according to the embodiment may be arranged and connected to suit the resolution.

Since the embodiment implements an image and an image using a micro light emitting device, color purity and color reproduction are excellent.

Since the embodiment implements images and images by using a micro light emitting device having excellent straightness, a clear large display device of 100 inches or more can be implemented.

In the above, the embodiment has been mainly described, but this is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in the range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (15)

transferring the plurality of micro light emitting devices formed on the first substrate to the first adhesive member;
transferring the plurality of micro light emitting devices from the first adhesive member to a second adhesive member; and
and transferring the plurality of micro light emitting devices from the second adhesive member to a second substrate,
The first temperature for controlling the first adhesive member in the step of transferring to the first adhesive member is a second temperature for controlling the first adhesive member and the second adhesive member in the step of transferring to the second adhesive member different,
The second temperature is different from a third temperature for controlling the second adhesive member and the conductive adhesive layer of the second substrate in the step of transferring to the second substrate,
The first temperature and the third temperature are higher than the second temperature,
The third temperature is higher than the first temperature,
The first temperature and the third temperature are lower than the curing completion temperature of the conductive adhesive layer,
The step of transferring to the first adhesive member,
disposing the first adhesive member on one surface of the plurality of micro light emitting devices; and
separating the plurality of micro light emitting devices from the first substrate by separating the first adhesive member from the first substrate;
In the disposing of the first adhesive member, the first adhesive member is heated to the first temperature to have the maximum adhesive strength, and the first adhesive member is bent so that the central portion of the first adhesive member is first the plurality of micro After attaching to one surface of the light emitting device, the edge of the first adhesive member is attached to the plurality of micro light emitting devices,
In the step of separating from the first substrate, the temperature of the first adhesive member is reduced to 70 to 80% of the first temperature to reduce the adhesive force of the first adhesive member from the maximum adhesive force, and then Lift one side to separate it,
The first substrate includes a plurality of protrusions respectively connected to the plurality of micro light emitting devices,
A width of the plurality of protrusions is smaller than a width of the micro light emitting device, and the plurality of protrusions are formed by etching one surface of the first substrate,
The protrusion has a long side and a short side, and a direction of a force separating the plurality of micro light emitting devices from the substrate crosses the long side.
delete delete delete delete delete According to claim 1,
The step of transferring to the second adhesive member,
disposing the second adhesive member on the other surfaces of the plurality of micro light emitting devices; and
After cooling the second adhesive member to the second temperature to adjust the adhesive force of the second adhesive member to be higher than that of the first adhesive member, the second adhesive member and the first adhesive member are spaced apart to make the plurality of A micro light emitting device transfer method comprising the step of separating the micro light emitting device from the first adhesive member.
8. The method of claim 7,
The maximum adhesive force of the first adhesive member and the second adhesive member is 0.8N/25mm to 2.0N/25mm.
8. The method of claim 7,
The thickness of the first adhesive member is 15㎛ or less micro light emitting device transfer method.
8. The method of claim 7,
The step of transferring from the second adhesive member to the second substrate,
The second adhesive member and the conductive adhesive layer of the second substrate are heated to the third temperature to adjust the adhesive strength of the conductive adhesive layer to be higher than that of the second adhesive member, and then, one surface of the plurality of micro light emitting devices is applied to the adhering to the conductive adhesive layer of the second substrate; and
and separating the plurality of micro light emitting devices from the second adhesive member by separating the second adhesive member from the second substrate.
11. The method of claim 10,
The step of transferring from the second adhesive member to the second substrate,
Before attaching one surface of the plurality of micro light emitting devices to the conductive adhesive layer of the second substrate, heating the second adhesive member to a fourth temperature and heating the second substrate to the third temperature including,
The fourth temperature is higher than the second temperature and lower than the third temperature.
11. The method of claim 10,
The conductive adhesive layer includes a plurality of conductive balls,
The thickness of the first electrode and the second electrode of the plurality of micro light emitting device is larger than the diameter of the conductive ball micro light emitting device transfer method.
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