KR102661676B1 - Method of fabricating display device - Google Patents

Abstract

According to an embodiment, the steps include inspecting a plurality of light emitting devices disposed on a first substrate; cutting a first area without any defective light emitting elements among the plurality of light emitting elements; and transferring a plurality of light emitting elements arranged in the cut first area to a panel.

Description

Display device manufacturing method {METHOD OF FABRICATING DISPLAY DEVICE}

The embodiment relates to a method of manufacturing a display device in which light-emitting elements are used as pixels.

Semiconductor devices containing compounds such as GaN and AlGaN have many advantages, such as having a wide and easily adjustable band gap energy, and can be used in a variety of ways, such as light emitting devices, light receiving devices, and various diodes.

In particular, light-emitting devices such as light emitting diodes and laser diodes using group 3-5 or group 2-6 compound semiconductor materials have produced red, green, and green colors through the development of thin film growth technology and device materials. Various colors such as blue and ultraviolet rays can be realized, and efficient white light can also be realized by using fluorescent materials or combining colors. Compared to existing light sources such as fluorescent lights and incandescent lights, low power consumption, semi-permanent lifespan, and fast response are possible. It has the advantages of speed, safety, and environmental friendliness.

In addition, when light-receiving devices such as photodetectors or solar cells are manufactured using group 3-5 or group 2-6 compound semiconductor materials, the development of device materials absorbs light in various wavelength ranges to generate photocurrent. By doing so, light of various wavelengths, from gamma rays to radio wavelengths, can be used. In addition, it has the advantages of fast response speed, safety, environmental friendliness, and easy control of device materials, so it can be easily used in power control, ultra-high frequency circuits, or communication modules.

Therefore, semiconductor devices can replace the transmission module of optical communication means, the light emitting diode backlight that replaces the cold cathode fluorescence lamp (CCFL) that constitutes the backlight of LCD (Liquid Crystal Display) display devices, and fluorescent or incandescent light bulbs. Applications are expanding to include white light-emitting diode lighting devices, automobile headlights and traffic lights, and sensors that detect gas or fire. Additionally, the applications of semiconductor devices can be expanded to high-frequency application circuits, other power control devices, and communication modules.

Recently, high-definition (HD) and large-screen display devices are in demand, but liquid crystal displays and organic electric field displays with complex configurations have low yields and high costs, making it difficult to implement high-definition large-screen displays.

The embodiment provides a method of manufacturing a display device with excellent yield.

Additionally, a method of manufacturing a display device with reduced manufacturing costs is provided.

A display device manufacturing method according to an embodiment of the present invention includes the steps of inspecting a plurality of light emitting devices disposed on a first substrate; cutting a first area without defective light emitting elements among the plurality of light emitting elements; and transferring the plurality of light emitting devices arranged in the cut first region to the panel.

The method may include selectively transferring a normal light emitting device onto the panel on the first substrate from which the first region is cut.

The step of transferring the plurality of light emitting devices arranged in the first area to the panel may include transferring the plurality of light emitting devices arranged in the first area to a temporary substrate; and transferring the light emitting device transferred to the temporary substrate to the panel.

At least one side of the first region may be 200 μm or more.

In the step of selectively transferring to the panel, the normal light emitting device may be separated from the first substrate on the first substrate in which the first region is cut and transferred to the panel.

In the step of selectively transferring to the panel, the normal light emitting device can be separated by selectively irradiating a laser on the first substrate.

According to the embodiment, a display device with excellent yield can be manufactured.

Additionally, production costs can be reduced.

The various and beneficial advantages and effects of the present invention are not limited to the above-described content, and may be more easily understood through description of specific embodiments of the present invention.

1 is a conceptual diagram of a display device according to an embodiment of the present invention;
Figure 2 is a conceptual diagram of a light emitting device,
Figure 3 is a top view of a wafer on which a plurality of light-emitting devices are grown;
Figure 4 is a diagram showing the process of cutting the first area where a plurality of normal light-emitting devices are gathered;
Figure 5 is a diagram showing the process of transferring the light emitting element of the first area to the panel;
Figure 6 is a top view of the transferred panel;
Figure 7 is a view showing a wafer from which the first region has been removed;
Figures 8a to 8c are diagrams showing the process of selectively transferring normal light emitting elements in the wafer;
Figure 9 is a top view of a panel on which selective transfer has been completed.

Hereinafter, embodiments of the present invention that can specifically realize the above object will be described with reference to the attached drawings.

In the description of the embodiment according to the present invention, in the case where each element is described as being formed "on or under", (or under) includes both elements that are in direct contact with each other or one or more other elements that are formed (indirectly) between the two elements. Additionally, when expressed as "on or under", it can include not only the upward direction but also the downward direction based on one element.

The semiconductor device may include various electronic devices such as a light-emitting device and a light-receiving device, and both the light-emitting device and the light-receiving device may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer.

The semiconductor device according to this embodiment may be a light emitting device.

Light-emitting devices emit light when electrons and holes recombine, and the wavelength of this light is determined by the material's inherent energy band gap. Accordingly, the light emitted may vary depending on the composition of the material.

Hereinafter, the semiconductor device of the embodiment will be described as a light emitting device.

FIG. 1 is a conceptual diagram of a display device according to an embodiment of the present invention, and FIG. 2 is a conceptual diagram of a light emitting device.

Referring to FIG. 1, a display device according to an embodiment includes a plurality of pixels 23 formed on an array substrate 20. The pixel 23 can be implemented as a light emitting diode (LED). Accordingly, power consumption is lowered, a long lifespan can be provided with low maintenance costs, and a high-brightness self-luminous display can be provided.

The pixel 23 may serve as an RGB subpixel by mounting the first to third light emitting elements (B, G, and R). Below, it is explained that three light emitting devices function as RGB subpixels, but the number of light emitting devices can be adjusted as needed.

The first light emitting device (B) may function as a first subpixel that outputs light in the blue wavelength range. The second light emitting device (G) may function as a second subpixel that outputs light in the green wavelength range. The third light emitting element (R) may function as a third subpixel that outputs light in the red wavelength range.

The second light emitting device (G) and the third light emitting device (R) can be converted into green light and red light by disposing the wavelength conversion layers 51 and 52 on the blue light emitting diode. The wavelength conversion layers 51 and 52 may include both phosphors or quantum dots (QDs). However, it is not necessarily limited to this, and the second light-emitting device may be a green light-emitting diode, and the third light-emitting device may be a red light-emitting diode.

The method of electrically connecting the first to third light emitting elements (B, G, and R) is not limited. Illustratively, the light emitting device may be electrically connected using a through electrode or a lead electrode.

The display device has SD (Standard Definition) resolution (760×480), HD (High definition) resolution (1180×720), FHD (Full HD) resolution (1920×1080), UH (Ultra HD) resolution (3480×2160), or UHD resolution. It can be implemented at higher resolutions (e.g. 4K (K=1000), 8K, etc.). At this time, the first to third light emitting devices (B, G, R) according to the embodiment may be arranged and connected in plural numbers according to the resolution.

The embodiment has the advantage of excellent color purity and color reproduction because a plurality of light-emitting devices function as pixels to implement images.

The embodiment implements videos and images using light-emitting devices with excellent straightness, so a clear large display device of 100 inches or more can be implemented.

The embodiment can implement a large display device of 100 inches or more with high resolution at low cost.

Referring to FIG. 2, the light emitting device is a light emitting structure 140 including a first conductive semiconductor layer 110, an active layer 120, and a second conductive semiconductor layer 130 disposed on an array substrate 20. ), a first electrode 150 extending from the side of the first conductive semiconductor layer 110 to the array substrate 20, an insulating layer 160 covering the side of the light emitting structure 140 and the first electrode 150. ), and a second electrode 170 disposed on the second conductive semiconductor layer 130.

The first conductive semiconductor layer 110 may be implemented with a compound semiconductor such as group III-V or group II-VI, and may be doped with a first dopant. The first conductive semiconductor layer 110 is a semiconductor material with a composition formula of InxAlyGa1-x-yN (0≤x≤≤1, 0≤≤y≤≤1, 0≤≤x+y≤≤1) or AlInN, It can be formed from a material selected from AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. When the first dopant is an n-type dopant such as Si, Ge, Sn, Se, Te, etc., the first conductive semiconductor layer 110 may be an n-type semiconductor layer.

The second conductive semiconductor layer 130 may be implemented with a compound semiconductor such as group III-V or group II-VI, and may be doped with a second dopant. The second conductive semiconductor layer 130 is a semiconductor material with a composition formula of AlxInyGa(1-x-y)N (0≤x≤≤1, 0≤≤y≤≤1, 0≤≤x+y≤≤1), It may be formed of any one or more of InAlGaN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP, but is not limited thereto. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, Ba, etc., the second conductive semiconductor layer 130 may be a p-type semiconductor layer.

The active layer 120 is provided between the first conductive semiconductor layer 110 and the second conductive semiconductor layer 130. The active layer 120 is a layer where electrons (or holes) injected through the first conductive semiconductor layer 110 and holes (or electrons) injected through the second conductive semiconductor layer 130 meet. The active layer 120 as described above transitions to a low energy level as electrons and holes recombine, and can generate light with a corresponding wavelength.

In order to display an image by placing a light emitting device in each pixel 23 of a display device and driving the light emitting device, the light emitting device must be electrically connected to the circuit pattern of the pixel 23. One end of the first electrode 150 is in contact with the first conductive semiconductor layer 110, and the other end extends to the upper surface of the array substrate 20 to be electrically connected.

The insulating film 160 may be arranged to surround the first electrode 150 and the light emitting structure 210a to expose a portion of the second conductive semiconductor layer 130. The insulating film 160 prevents electrical connection between the first electrode 150 and the second electrode 170. The insulating film 160 as described above may be formed by selecting at least one from the group consisting of SiO2, SixOy, Si3N4, SixNy, SiOxNy, Al2O3, TiO2, AlN, etc., but is not limited thereto.

The second electrode 170 may be electrically connected to the second conductive semiconductor layer 130 exposed by the insulating film 160. Although not shown, an ohmic layer may be further disposed between the second conductive semiconductor layer 130 and the second electrode. Current can be uniformly spread from the second electrode 170 to the second conductive semiconductor layer 130 through the ohmic layer.

Figure 3 is a plan view of a wafer on which a plurality of light-emitting devices are grown, Figure 4 is a diagram showing the process of cutting the first region where a plurality of normal light-emitting devices are gathered, and Figure 5 is a diagram showing the light-emitting devices of the first region on the array substrate. This is a diagram showing the transfer process, and Figure 6 is a top view of the transferred array substrate.

A display device manufacturing method according to an embodiment of the present invention includes the steps of inspecting a plurality of light-emitting devices disposed on a first substrate 10, a first region ( It includes cutting 11) and transferring a plurality of light emitting devices arranged in the cut first region 11 to the array substrate 20.

Referring to FIG. 3, a plurality of light emitting devices 100 and 200 may be disposed on the first substrate 10. The first substrate 10 may be a wafer substrate, and the plurality of light emitting devices 100 and 200 may be epi structures grown on a wafer.

For example, even when a plurality of light emitting devices are grown using the same method on a single wafer, some light emitting devices may be defective. Defects can be caused by various causes. For example, defects may include cases where light is not emitted, the intensity of light does not meet the standard value, or the emission wavelength range is outside the standard range.

Hereinafter, light-emitting devices that do not pass the standards are defined as defective light-emitting devices, and light-emitting devices that pass the standards are defined as normal light-emitting devices.

However, in the case of 1:1 transfer of the first substrate 10 to the array substrate 20, there is a problem of low yield because even the defective light emitting devices 200 are transferred. Additionally, when only normal light-emitting devices are selectively transferred, the process takes longer because many chips must be controlled one by one. In particular, it is difficult to maintain light uniformity because it is difficult to align each chip in the same direction.

In an embodiment, the first area 11 without any defective light emitting devices 200 among the plurality of light emitting devices is cut. Referring to FIG. 3, a plurality of defective first areas 11 are selected, and the first areas 11 are cut as shown in FIG. 4. The method of cutting the first area 11 is not particularly limited. It can also be cut using general scribing.

Thereafter, the plurality of light emitting devices arranged in the cut first region 11 are transferred to the array substrate 20.

Specifically, after bonding the substrate to the array substrate 20, laser lift off (LLO) may be performed on the entire substrate so that the light emitting elements are separated and transferred to the array substrate 20.

Through this process, a plurality of first regions 11 are sequentially transferred to the array substrate 20, so that defect-free light emitting devices can be transferred to the array substrate 20 at a high speed.

At this time, the size of the first area 11 can be manufactured to be 200x200um or more. If the size of the first area 11 is 200x200um or more, it can be transferred with a general transfer device (e.g., robot arm, vibrating chuck, etc.), so there is an advantage that existing equipment can be used as is.

FIG. 7 is a view showing a wafer from which the first region has been removed, FIGS. 8A to 8C are views showing a process of selectively transferring normal light emitting devices in the wafer, and FIG. 9 is a plan view of an array substrate on which selective transfer has been completed.

Referring to FIG. 7, the normal light emitting device 100 remaining on the first substrate 10 from which the first region 11 has been removed can be transferred to the array substrate 20.

Specifically, as shown in FIG. 8A, the first substrate 10 is adhered to each other, and as shown in FIG. 8B, the laser 30 is irradiated only to the area where the normal light emitting device is placed to lift off. Thereafter, when the first substrate 10 is separated, only the normal light emitting device 100 can be selectively transferred to the array substrate 20.

According to this method, the array substrate 20 with a 100% yield can be manufactured by measuring grouped light emitting devices and excluding groups that have defects in advance. In the case of 1:1 transfer, if a defect occurred, the entire wafer had to be discarded because it continued through the transfer. However, according to the embodiment, costs are reduced because only defective light emitting devices can be selected and the remaining light emitting devices can be used.

Additionally, when producing a large-area display with micro LED, it is difficult to adopt a 1:1 transfer method because it is difficult to obtain a large-area wafer. Additionally, selective transcription has the problem of taking a long transcription time. However, according to the embodiment, the normal light emitting devices in the first area are transferred 1:1 and the remaining light emitting devices are selectively transferred, thereby improving yield and reducing costs.

Claims (6)

inspecting a plurality of light emitting devices arranged on a first substrate;
cutting a first area in which there is no defective light emitting device among the plurality of light emitting devices from the first substrate;
transferring a plurality of light emitting devices arranged in the first area to a panel;
adhering the first substrate, from which the first region is cut, to the panel; and
A step of selectively irradiating a laser only to the area where the normal light-emitting device remaining on the first substrate from which the first region was cut is disposed, separating the normal light-emitting device from the first substrate and selectively transferring it to the panel. Includes,
The light emitting device includes a light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, a first electrode extending from a side of the first conductive semiconductor layer to the panel, and the first electrode. and a display device comprising an insulating layer surrounding the light emitting structure and exposing a portion of the second conductive semiconductor layer, and a second electrode electrically connected to the second conductive semiconductor layer exposed by the insulating layer. Manufacturing method.
delete According to paragraph 1,
The step of transferring the plurality of light emitting elements arranged in the first area to the panel,
transferring a plurality of light emitting devices arranged in the first area to a temporary substrate; and
A display device manufacturing method comprising transferring the light emitting element transferred to the temporary substrate to the panel.
According to paragraph 1,
A method of manufacturing a display device wherein at least one side of the first area is 200um or more.
delete delete

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