LED transfer method with improved LED chip transfer position accuracy and display device manufactured by same method

Abstract

The present invention relates to an LED chip transfer method and, more specifically, to an LED transfer method capable of increasing the accuracy of an LED chip positioned when transferring the LED chip from a substrate to a substrate. The LED transfer method with improved LED chip transfer position accuracy according to an embodiment of the present invention is characterized in that a corresponding LED chip is selectively transferred by expanding a photosensitive transfer resin layer from a donor substrate to an acceptor substrate, and the expansion of the photosensitive transfer resin layer is vertically raised so that a surface in contact with the LED chip is expanded while maintaining a flat surface.

Description

LED transfer method for improving LED chip transfer position accuracy and display device manufactured by the method

[0001] The present invention relates to a transfer method for LED chips, and more particularly, to an LED transfer method capable of improving the accuracy of positioning LED chips when transferring LED chips from a substrate to a substrate.

[0002] A light-emitting diode (LED) is a type of light-emitting device that emits light when current is applied. Because LEDs can emit high-efficiency light at low voltages, they offer excellent energy-saving benefits.

[0003] Recently, the brightness problem of light-emitting diodes has been greatly improved, and they are being applied to various devices such as backlight units of liquid crystal displays, electronic billboards, indicators, and home appliances.

[0004] The size of micro light-emitting diodes (μ-LEDs) is very small, ranging from 1 to 100 μm, and approximately 25 million pixels are required to implement a 40-inch display device.

[0005] Therefore, there is a problem that it takes at least a month to make one 40-inch display device using a simple pick and place method.

[0006] Conventional micro light-emitting diodes (μ-LEDs) are manufactured in multiple units on a sapphire substrate, and then transferred one by one to a glass or flexible substrate using a mechanical transfer method called pick and place.

[0007] Currently, various transfer methods, such as elastomer stamp technology, laser-guided technology, fluid transfer technology, electrostatic transfer technology, and roll-to-roll (R2R) technology, are being developed to transfer micro LED chips from one substrate to another. However, it has been difficult to achieve chip positional accuracy due to positional errors during transfer.

[0008] The most important criterion for performing the micro LED chip transfer process from one substrate to another is positional accuracy.

[0009] Large positional errors or large chip tilts can result in electrical connections not being achievable, negating the benefits of chip transfer.

[0010] In general, a donor film is used to transfer an LED chip from a donor substrate to an acceptor substrate when transferring an LED chip using laser-guided technology. However, when a laser is irradiated on the donor film, the donor film expands into a dome shape, which causes the positional accuracy of the LED chip to be destroyed and interference between LED chips to be caused.

[0011] [Prior Art Literature]

[0012] [Patent Document]

[0013] (Patent Document 1) Republic of Korea Publication No. 10-2023-0057640

[0014] The present invention, which aims to solve the above-described problem, aims to provide a transfer method that can fundamentally block interference between LED chips by enabling separation and transfer of chips through expansion (expansion) only in an area smaller than a micro LED chip.

[0015] In addition, the present invention seeks to provide a transfer method that can prevent tilting of the LED chip during transfer and minimize errors in transfer position by separating the chip in a flat form with an expanded (inflated) upper surface within the LED chip area.

[0016] In addition, the LED chip pitch on the wafer is minimized by preventing tilting of the LED chip during LED chip transfer and interference between LED chips, thereby increasing the LED chip Net Die on the wafer and improving productivity.

[0017] The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0018] An LED transfer method for improving the accuracy of LED chip transfer position according to an embodiment of the present invention for solving the above-described problem may be achieved by selectively transferring the LED chip by expanding a photosensitive transfer resin layer from a donor substrate to an acceptor substrate, and the expansion of the photosensitive transfer resin layer is characterized by vertically protruding so that the surface in contact with the LED chip is expanded while maintaining a flat surface.

[0019] Here, it is preferable that the width of the photosensitive transfer resin layer upon expansion be formed smaller than the width of the LED chip.

[0020] Here, the height of the photosensitive transfer resin layer before and after expansion increases, and the width does not change, which can bring about the effect of positive vertical uplift.

[0021] Here, it is preferable that the pitch of the LED chip on the donor substrate is within ±1.0 ㎛ of the design reference value, and the pitch of the LED chip on the acceptor substrate is within ±1.2 ㎛ of the design reference value.

[0022] Here, when the photosensitive transfer resin layer expands, it is preferable that there is no tilting of the photosensitive transfer resin layer.

[0023] Here, by maintaining the vertical elevation and flat surface of the photosensitive transfer resin layer, the pitch between LED chips on the wafer can be reduced, thereby improving the Net Die.

[0024] In addition, a display device according to an embodiment of the present invention can be manufactured by an LED transfer method that improves the accuracy of LED chip transfer position.

[0025] According to the configuration of the present invention described above, separation and transfer of chips by expansion (expansion) are possible only in an area smaller than the micro LED chip, thereby fundamentally blocking interference between LED chips.

[0026] In addition, since the expanded (inflated) upper surface within the LED chip area separates the chip into a flat shape and is transferred, tilting of the LED chip during transfer can be prevented and errors in the transfer position can be minimized.

[0027] In addition, by preventing tilting of LED chips during LED chip transfer and interference between LED chips, the pitch of LED chips on the wafer can be minimized, thereby increasing the Net Die of LED chips on the wafer and improving productivity.

[0028] However, the effects of the present invention are not limited to the above-described effects, and may be expanded in various ways without departing from the spirit and scope of the present invention.

[0029] Figure 1 is a process diagram for growing Epi on a wafer according to an embodiment of the present invention.

[0030] FIG. 2 is a process diagram for transferring a grown LED chip from a wafer to a glass (donor) substrate according to an embodiment of the present invention.

[0031] Figure 3 is a process diagram for removing a wafer according to an embodiment of the present invention.

[0032] FIG. 4 is a process diagram for selectively transferring LED chips from a donor substrate to an acceptor substrate according to an embodiment of the present invention.

[0033] FIG. 5 is a process diagram for selectively transferring a chip array from an acceptor substrate to a backplane according to an embodiment of the present invention.

[0034] Figure 6 is a SEM (Scanning Electron Microscope) photograph before and after PR expansion according to an embodiment of the present invention.

[0035] Figure 7 is a position data drawing of a mask pattern according to an embodiment of the present invention.

[0036] FIG. 8 is a diagram showing the position data of an LED chip on a donor substrate according to an embodiment of the present invention.

[0037] FIG. 9 is a diagram showing the position data of an LED chip on an acceptor substrate according to an embodiment of the present invention.

[0038] Figure 10 is an exemplary drawing comparing a Net Die on a wafer of an embodiment of the present invention and a conventional technology.

[0039] In the description of the embodiment, when it is described as being formed “above or below” each component, “above” or “below” includes both two components being in direct contact with each other or one or more other components being disposed between two components.

[0040] Additionally, when expressed as "upper or lower", it can include the meaning of not only the upward direction but also the downward direction based on one component.

[0041] In the drawings, the thickness and size of each layer are exaggerated, omitted, or schematically illustrated for convenience and clarity. Furthermore, the size of each component does not entirely reflect its actual size.

[0042] The chip used in the present invention is a concept that includes all of LED chips, RGB chips, R chips, G chips, B chips, mini LED chips, and micro LED chips.

[0043] Hereinafter, for convenience of explanation, the chip is described as an R chip, a G chip, or a B chip, but it should be noted that the chip is not limited to an R chip, a G chip, or a B chip.

[0044] The present invention utilizes the expansion principle of photosensitive resin.

[0045] That is, when UV is irradiated on the photosensitive resin (PR, Photo Resist), a photoreaction occurs in the internal novolak resin and photoactive agent, and acid is generated. This acid is in a liquid state, and when the wafer is placed on a hot plate and temperature is applied, only the area irradiated with UV expands. The expansion occurs when the liquid acid trapped inside the PR rapidly increases in volume due to heat.

[0046] Here, a photoactive agent is added to increase the expansion power of the photosensitive resin to enable transfer of the LED chip, thereby increasing the amount of acid in the PR and increasing the expansion power of the PR, thereby preventing the cause of defects during transfer.

[0047] Photoactive agent is a comprehensive term that refers to any one of photoacid generator (PAG), photoactive compound (PAC), photoinitiator, photosensitive compound or photoactive compound.

[0048] The photosensitive resin may be composed of a novolac resin, a solvent, and a photoactivator. The solvent may be PGMEA or ethyl lactate, and the photosensitive transfer resin may be defined as a resin in which a photoactivator solution is added to the photosensitive resin.

[0049] The transfer process from the wafer to the display panel using the PR expansion described above will be described in more detail with reference to FIGS. 1 to 5.

[0050] Figure 1 is a process diagram for growing Epi on a wafer according to an embodiment of the present invention.

[0051] Referring to Fig. 1, an epitaxial layer (11) that emits a predetermined amount of light is grown on one surface of each wafer (10).

[0052] Here, the wafer (10) may be any one of sapphire (Al2O3), silicon, gallium arsenide (GaAs), gallium nitride (GaN), and zinc nitride (ZnN). However, it is not limited thereto, and any substrate that can be used as a wafer may be used.

[0053] A pad (13) is formed on each grown epi (11).

[0054] The light emitting body formed on the wafer (10) is electrically separated by chip unit, and is referred to as an LED chip in the present invention. Afterwards, each chip is etched and can be transferred from the wafer (10) to a glass substrate.

[0055] Here, the epi (11) on the wafer (10) includes an RGB (red, green, blue) epi, and an example of growing one epi (11) on one wafer (10) is shown as a representative example, and each RGB epi can be grown on three wafers to form one pixel of an RGB LED chip.

[0056] Figure 2 is a process diagram for transferring the etched chip of Figure 1 from a wafer to a donor substrate, and Figure 3 is a process diagram for removing the wafer.

[0057] Figures 2 and 3 are processes for transferring an etched chip to a donor substrate (20) and removing the wafer (10) after transfer.

[0058] In the drawings below, one chip (100) is depicted as a chip formed in FIG. 1, but is not limited thereto and may be an RGB chip array etched in the row and column directions.

[0059] In addition, in the present invention, the chip (100) can be manufactured into a new concept of small packaging in the form of a CSP by configuring sub-pixels for each of R, G, and B.

[0060] The R LED chip, the G LED chip, and the B LED chip can constitute one light-emitting element or light-emitting body and form one pixel.

[0061] A pre-process can be performed to transfer a chip array by attaching a plurality of LED chips (100) to a donor substrate in the row and column directions, and the chips can be sequentially or selectively transferred from the donor substrate to an acceptor substrate and a backplane ((TFT (Thin Film Transistor) substrate) to be described later.

[0062] A process of attaching chip arrays etched in the form of LED chips (100) on a wafer (10) to a donor substrate and removing the wafer is performed, and then a process of sequentially transferring or selectively transferring the chip arrays from the donor substrate to an acceptor substrate and a display panel is examined.

[0063] Referring to Fig. 2, after the chips are separated in the matrix direction by etching, the donor substrate (20) is attached to the LED chip (100) in the opposite direction of the wafer (10).

[0064] That is, the donor substrate (20) is attached to the pad (13) side of the LED chip (100).

[0065] The donor substrate (20) may include a substrate (21) and a photosensitive transfer resin layer (23).

[0066] The substrate (21) may be composed of any one of glass, quartz, synthetic quartz, and metal, and the material is not particularly limited.

[0067] The photosensitive transfer resin layer (23) may be a photosensitive resin containing a photoactive agent in a predetermined weight percent (wt%) or more.

[0068] Referring to FIG. 3, when the wafer (10) is removed by the LLO (Laser Lift Off) or CLO (Chemical Lift Off) process in the same state as FIG. 2, the LED chip (100) is placed in a state attached to the donor substrate (20), and at this time, the direction of the LED chip (100) is placed in a state in which the light emitting body is exposed in the opposite direction.

[0069] The donor substrate (20) may include a donor substrate on which an R LED chip array is formed according to epi growth, a donor substrate on which a G LED chip array is formed, and a donor substrate on which a B LED chip array is formed.

[0070] Figure 4 is a process diagram for explaining a process of selectively transferring a chip array from a donor substrate to an acceptor substrate.

[0071] Referring to (A) of Fig. 4, an acceptor substrate (30) is placed on a donor substrate (20) on which an LED chip (100) is formed.

[0072] The adhesive layer (33) of the acceptor substrate (30) is brought into contact with the LED chips (100) so that they are attached to each other.

[0073] Here, the acceptor substrate (30) may be composed of a substrate (31) and an adhesive layer (33).

[0074] Referring to (B) of Fig. 4, a mask (40) is placed on the back surface of the donor substrate (20) while the donor substrate (20) and the acceptor substrate (30) are positioned facing each other with the LED chip (100) interposed therebetween, as in (A).

[0075] The mask (40) may be a pre-patterned mask.

[0076] UV is irradiated while the mask (40) is placed.

[0077] Only a specific area of ​​the photosensitive transfer resin layer (23) can be exposed by the mask (40) pattern and UV irradiation.

[0078] Here, the 'Exposure' can be adjusted in terms of the degree of exposure depending on the control of UV exposure energy.

[0079] The controlled exposure portion of the photosensitive resin according to the amount of UV irradiation can be called the photo-induced activation layer.

[0080] The photoactive layer can selectively transfer only the LED chip at the corresponding location by expanding the transfer resin and reducing the adhesive force of the LED chip as heat is applied.

[0081] Referring to (C) of Fig. 4, heat is applied to the upper portion of the donor substrate (20).

[0082] At this time, heat may mean the expandable temperature of the photosensitive transfer resin layer (23).

[0083] When heat is applied to the donor substrate (20) to a temperature at which the photosensitive transfer resin layer (23) can expand, the photosensitive transfer resin layer (23) becomes a photosensitive transfer resin layer (23') whose volume has expanded, and at this time, the location at which the volume can expand can be the area where the photoactive layer that has been developed in (B) exists.

[0084] The photosensitive transfer resin layer (23') whose volume has expanded increases in size and pushes out the LED chip (100) by the pressure (expansion force) when the volume has expanded, thereby reducing the adhesive force of the LED chip (100) to zero, and the LED chip (100) adhered to that position is peeled off (or transferred) and becomes capable of being transferred to the acceptor substrate (30).

[0085] The LED chip (100) that has expanded and lost its adhesive strength can be selectively transferred only to the required LED chip (100) among the LED chips (100) on the donor substrate (20) by approaching and picking up the acceptor substrate (30).

[0086] At this time, since the transfer of the LED chip (100) can selectively transfer only the necessary LED chip (100) according to the pattern of the mask (40), the LED chip (100) transferred from the donor substrate (20) to the acceptor substrate (30) can be subject to selective transfer.

[0087] Referring to (D) of FIG. 4, it can be seen that only a specific LED chip (100) is selectively peeled off and transferred from the donor substrate (20) to the acceptor substrate (30).

[0088] FIG. 5 is a process diagram illustrating a process of selectively transferring a chip array from an acceptor substrate to a backplane according to an embodiment of the present invention.

[0089] Fig. 5 is described based on only one LED chip among the RGB LED chips of Figs. 1 to 4.

[0090] A backplane (TFT substrate (50)) is placed on the acceptor substrate (30) on which the LED chip (100) is transferred and positioned.

[0091] A plurality of pads (51) are formed on the backplane (50), and solder paste can be applied on the plurality of pads (51).

[0092] The backplane (50) can be defined to include a structure in which the display panel and the TFT array substrate are arranged vertically.

[0093] LED chips (100) attached to the acceptor substrate (30) are placed on the backplane (50), and the pads of the LED chips (100) are arranged on the pads (51) of the backplane (50).

[0094] The acceptor substrate (30) and the backplane (50) are placed facing each other with the LED chip (100) between them.

[0095] All LED chips are transferred from the acceptor substrate (30) to the backplane (50) by applying heat or laser to the upper portion of the acceptor substrate (30).

[0096] By repeatedly performing these processes, it becomes possible to sequentially transfer R, G, and B LED chips onto the backplane (50) in order of time intervals.

[0097] Figure 6 is a SEM (Scanning Electron Microscope) photograph before and after PR expansion according to an embodiment of the present invention.

[0098] Referring to Fig. 6, (A) is a SEM (Scanning Electron Microscope) photograph before expansion of the photosensitive transfer resin layer (23), and (B) is a SEM (Scanning Electron Microscope) cross-sectional photograph after expansion of the photosensitive transfer resin layer (23).

[0099] The SEM image (A) before expansion shows the plan view, the width of each chip is 49.0 μm, and the width and distance between chips are 10.5 μm / 10.7 μm.

[0100] The SEM cross-sectional photograph (B) after expansion is a photograph showing the YY cross-section of (C) in Fig. 4.

[0101] A cross-section of a photosensitive transfer resin layer (23) is visible on the substrate (21) of the donor substrate (20), and the photosensitive transfer resin layer (23) is in an expanded state.

[0102] It can be seen that the photosensitive transfer resin layer (23) has a width of 36.6 ㎛, which is smaller than the width of the LED chip of 49.0 ㎛, and the height before expansion is 6.09 ㎛ and the height after expansion is 8.20 ㎛, so the viscosity becomes zero after expansion.

[0103] The width of the photosensitive transfer resin layer (23) before and after expansion is 36.6 μm, and it can be seen that there is no change before and after expansion. This shows that expansion occurs due to vertical protrusion in the positive direction when the photosensitive transfer resin layer (23) is expanded.

[0104] It can be seen that the inclination of the photosensitive transfer resin layer (23) does not change before and after expansion.

[0105] Since the photosensitive transfer resin layer (23) maintains a flat upper surface even after expansion, as shown in the SEM cross-sectional photograph, the LED chip (100) positioned thereon is transferred vertically upward, so there is no influence of positional error due to tilting, and there is no interference effect due to transfer of adjacent LED chips.

[0106] After the photosensitive transfer resin layer (23) expands, the photosensitive transfer resin layer (23) is raised in the vertical direction, and the LED chip (100) at the raised position is already transferred and is not visible in the photograph, and the LED chip (100') visible at the top is an adjacent LED chip (i.e., an unselected LED chip that is not transferred) located behind the LED chip (100).

[0107] The fact that the LED chip (100') on the back appears to be tilted is a result of physical impact that occurred during the production of the SEM (Scanning Electron Microscope) sample.

[0108] FIGS. 7 to 9 illustrate photographs, error data, and graphs thereof for explaining the accuracy of the position of a mask pattern, the position of an LED chip on a donor substrate, and the position of an LED chip on an acceptor substrate, according to an embodiment of the present invention.

[0109] Figure 7 is a position data drawing of a mask pattern according to an embodiment of the present invention.

[0110] Referring to FIG. 7, the mask (40) forms a pattern at the position of the LED chip (100) to be transferred, as in (B) of FIG. 4, and the position of the pattern is related to the size of the LED chip (100) and the pitch with respect to the adjacent LED chip.

[0111] 1 pattern represents the pitch between the first pattern and the second pattern, and 2 pattern represents the pitch between the first pattern and the third pattern.

[0112] As a design standard, pattern 1 is 240㎛ and the actual measurement value is 239.7㎛, and pattern 2 is 480㎛ and the actual measurement value is 479.4㎛.

[0113] When selectively transferring from the donor substrate (20) to the acceptor substrate (30) based on pattern 1 and pattern 2 of the mask (40), the pitch data of the LED chip (100) positioned on the donor substrate (20) and the acceptor substrate (30) are examined with reference to FIGS. 8 and 9.

[0114] FIG. 8 is a diagram showing the position data of an LED chip on a donor substrate according to an embodiment of the present invention.

[0115] Referring to Fig. 8, 20a to 20d are photographs of parts of the donor substrate (20) combined together, and are photographs measuring the lengths of pattern 1 and pattern 2 between each chip.

[0116] 20-1 is a table showing the difference in the x and y axes based on the first LED chip in the length data of pattern 1 and pattern 2, and 20-2 is a graph showing the data table of 20-1.

[0117] As a result of measuring the length of pattern 1 and pattern 2 on the xy axis based on the first LED chip (the LED chip at the lower left of 20c), it can be confirmed that each LED chip is within the range of ±1.0㎛, which is within the range of 10% of the actual distance between LED chips of 10.5㎛ / 10.7㎛ (Fig. 6), so that there is almost no change in position due to transfer of the LED chip, and it can be seen that large-capacity / large-area transfer is possible using the transfer method of the present invention.

[0118] FIG. 9 is a diagram showing the position data of an LED chip on an acceptor substrate according to an embodiment of the present invention.

[0119] Referring to Fig. 9, 30a to 30d are photographs of parts of the acceptor substrate (30) combined together, and are photographs measuring the lengths of pattern 1 and pattern 2 between each chip.

[0120] 30-1 is a table showing the difference in the x and y axes based on the first LED chip in the length data of pattern 1 and pattern 2, and 30-2 is a graph showing the data table of 30-1.

[0121] As a result of measuring the length of pattern 1 and pattern 2 on the xy axis based on the first LED chip (the LED chip at the lower left of 30c), it can be confirmed that each LED chip is within the range of ±1.2㎛, which is within the range of 10% of the actual distance between LED chips of 10.5㎛ / 10.7㎛ (Fig. 6), so that there is almost no change in position due to transfer of the LED chip, and it can be seen that large-capacity / large-area transfer is possible using the transfer method of the present invention.

[0122] As shown in FIGS. 8 and 9, there is no change in the pitch of the LED chips transferred from the wafer (10) to the donor substrate (20), and it can also be seen that there is almost no change in the pitch of the LED chips selectively transferred from the donor substrate (20) to the acceptor substrate (30). This suggests that, as shown in the photograph of FIG. 6, the photosensitive transfer resin layer (23) of the present invention expands vertically when expanded and maintains a flat upper surface, so there is almost no change in the pitch of the LED chips even after several transfers.

[0123] Figure 10 is an exemplary drawing comparing a Net Die on a wafer of an embodiment of the present invention and a conventional technology.

[0124] Referring to FIG. 10, FIG. 10 shows that a very economical production method can be implemented by increasing the number of LED chips (Net Die) that can be epitaxially grown on a wafer according to the transfer method of the present invention as in FIGS. 1 to 5 and the positional accuracy as in FIGS. 6 and 9.

[0125] (A) shows an array structure of LED chips that can be formed on a wafer when transferring LED chips using a conventional laser-guided technology, and (B) shows an array structure of LED chips by PR expansion (expansion that maintains a flat surface after vertical protrusion and expansion of a surface in contact with the LED chip) according to the present invention.

[0126] In (A) and (B), the array structure in the same area is shown when the size of the LED chip is 15㎛ x 30㎛.

[0127] As in (A), interference between adjacent LED chips is induced due to the dome structure of the donor film during transfer using laser-guided technology, and the number of LED chips that can be epitaxially formed on a given wafer area is limited due to the positional inclination of each chip being different from each other due to the enlarged transfer of the dome structure.

[0128] That is, the edge-to-edge distance between chips should be 30㎛, and accordingly, the LED chip pitch becomes 45㎛ / 60㎛, and with a 7*5 chip array arrangement (285㎛ x 270㎛), approximately 35 LED chips can be epitaxially grown.

[0129] On the other hand, since there is no interference between adjacent LED chips and no tilting of the positions of each chip due to the vertical protrusions and flat protrusion surfaces during PR expansion transfer according to the present invention, as in (B), the number of LED chips that can be epitaxially formed on a given wafer area increases.

[0130] That is, 3㎛ is sufficient for the edge-to-edge distance between chips, and accordingly, the LED chip pitch becomes 18㎛ / 33㎛, and with a 16*8 chip array arrangement (285㎛ x 261㎛), approximately 128 LED chips can be epitaxially grown.

[0131] This shows that the transfer technology of the present invention can have a Net Die production efficiency of three times or more on a wafer of the same area compared to the conventional laser-induced transfer technology.

[0132] The features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment can be combined or modified in other embodiments by those skilled in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as falling within the scope of the present invention.

[0133] In addition, although the above description focuses on embodiments, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present embodiment. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

[0134] [Explanation of symbols]

[0135] 10: Wafer

[0136] 100: LED chip

[0137] 20: Donor substrate

[0138] 30: Acceptor substrate

[0139] 40: Mask

[0140] 50: Backplane

Claims

1. Selectively transfer the LED chip by expanding the photosensitive transfer resin layer from the donor substrate to the acceptor substrate, An LED transfer method that improves the accuracy of LED chip transfer positioning, wherein the photosensitive transfer resin layer expands vertically while maintaining a flat surface on the surface that contacts the LED chip.

2. In paragraph 1, An LED transfer method for improving the accuracy of LED chip transfer positioning, wherein the width of the photosensitive transfer resin layer upon expansion is smaller than the width of the LED chip.

3. In paragraph 1, An LED transfer method for improving the accuracy of LED chip transfer positioning, wherein the height before and after expansion of the photosensitive transfer resin layer increases and the width does not change.

4. In paragraph 1, The pitch of the LED chip on the donor substrate is within ±1.0 ㎛ of the design reference value, An LED transfer method for improving the accuracy of LED chip transfer position, wherein the pitch of the LED chip on the acceptor substrate is within ±1.2 ㎛ of the design reference value.

5. In paragraph 1, An LED transfer method that improves the accuracy of LED chip transfer position without tilting of the photosensitive transfer resin layer when the photosensitive transfer resin layer expands.

6. In paragraph 1, An LED transfer method for improving the accuracy of LED chip transfer position by reducing the pitch between LED chips on a wafer and improving the Net Die by maintaining the vertical elevation and flat surface of the photosensitive transfer resin layer.

7. A display device manufactured by an LED transfer method that improves the LED chip transfer position accuracy of any one of claims 1 to 6.

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