KR102321518B1 - Led chip transferring apparatus using photoresist resin - Google Patents

Abstract

The present invention provides a technology of transferring an LED chip formed on a wafer to a substrate or a display panel and relates to an LED chip transferring apparatus where the technology of transferring a part of each chip attached to a substrate to another carrier substrate and a display panel selectively, sequentially or at intervals by using a transfer resin which can be expanded by light is applied. The LED chip transferring apparatus using a photosensitive resin in accordance with an embodiment of the present invention comprises: a substrate; and a photosensitive resin layer composed of a photosensitive resin which is expanded at a predetermined temperature and formed on the substrate, whose particular area is exposed to light by UV emission to form a photodegrade layer, wherein the LED chip is formed on the photosensitive resin layer, a lower part of the LED chip is stuck in the photosensitive resin layer by a clip-up structure, and predetermined heat is applied to expand the photodegrade layer. Moreover, adhesive force of the LED chip disposed on the photodegrade layer is offset to exfoliate or transfer the LED chip.

Description

LED chip transfer device using photosensitive resin {LED CHIP TRANSFERRING APPARATUS USING PHOTORESIST RESIN}

The present invention is a technology for transferring an LED chip formed on a wafer to a substrate or a display panel, and a part of each chip attached to the substrate is selectively and sequentially transferred to another carrier substrate and display panel using a photosensitive resin that is expanded by light. Or it relates to an LED chip transfer device to which the transfer technology is applied at a time interval.

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 a 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.

The size of a micro light emitting diode (μ-LED) is very small, ranging from 1 to 100 μm, and approximately 25 million or more pixels are required to implement a 40-inch display device.

Therefore, there is a problem that it takes at least a month in terms of time by a simple pick and place method to make one 40-inch display device.

Existing micro light emitting diodes (μ-LED) are manufactured in plurality on a sapphire substrate, and then, by a mechanical transfer method, pick & place, micro light emitting diodes are placed on glass or flexible substrate one by one. are transcribed

Since the micro light emitting diodes are picked up one by one and transferred, it is referred to as a 1:1 pick-and-place transfer method.

However, since the size of the micro light emitting diode chip manufactured on the sapphire substrate is small and the thickness is thin, the chip is damaged or the transfer fails, or the chip alignment ( Alignment) fails, or a problem such as a tilt of the chip is generated.

In addition, there is a problem that the time required for the transcription process is too long.

Japanese Patent Application Laid-Open No. 2019-015899 discloses a technique for exfoliating by expanding thermally expansible particles to weaken the adhesive force as a transfer method of chip parts, but uniform mixing of thermally expansible particles and uniform adhesive force due to thermal expansion There are difficulties such as securing technology.

Republic of Korea Patent Registration 10-0853410 Japanese Unexamined Patent Application Publication No. 2019-015899

An object of the present invention is to provide an LED chip transfer device capable of transferring a plurality of chips formed or disposed on a base substrate by using the photoactivity and expansibility of a photosensitive resin.

Another object of the present invention is to provide an LED chip transfer device capable of selectively transferring a plurality of chips formed on a base substrate using a predetermined resin.

In addition, it is intended to manufacture a display device having a variety of pitches by enabling micro-unit LED chips to be transferred according to required sizes without errors.

The problem to be solved of the present invention is not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be.

An LED chip transfer apparatus using a photosensitive resin according to an embodiment of the present invention includes: a substrate; and a photosensitive resin layer formed on the substrate, a specific area exposed to UV irradiation to form a photodegradation layer, and made of a photosensitive resin that expands at a predetermined temperature, wherein an LED chip is disposed on the photosensitive resin layer The lower part of the LED chip is placed in a state embedded in the photosensitive resin layer by a clip-up structure, the photodegradation layer is expanded by applying a predetermined heat, and the LED chip located in the photodegradation layer It is a transfer device that cancels the adhesive force of the LED chip so that the LED chip can be peeled or transferred.

Here, the photosensitive resin may be prepared by mixing a base resin, an organic solvent, and a photoactive agent.

Here, in the photosensitive resin, a specific region is exposed by a mask and UV irradiation to form a photodegradation layer, and by applying a predetermined heat, the photodegradation layer is expanded to selectively transfer only the LED chip located in the photodegradation layer.

Here, the photosensitive resin may further include a solvent.

Here, a filler for reinforcing the adhesive force of the LED chip may be added to the photosensitive resin.

Here, DI water may be added to the photosensitive resin.

According to the above-described configuration of the present invention, there is an advantage in that a plurality of chips formed or disposed on the base substrate can be selectively transferred using predetermined UV and heat.

In addition, it is possible to provide a resin capable of transferring a plurality of chips formed on the base substrate by offsetting the adhesive force of the LED chip by forming a photodegradation layer through target exposure of a predetermined resin layer, and applying heat thereto to expand.

In addition, it is possible to provide this as a transfer resin by using the deterioration and expansion characteristics of the photoactivator (photoinitiator), thereby increasing the ease of manufacture, lowering the manufacturing cost, and zeroing the transfer error of the micro-unit LED chip.

In addition, it is possible to have a clip-up structure that allows the LED chip to be embedded in the resin to minimize the peeling of the LED chip attached to the resin, so that it is possible to zero the error in display panel manufacturing due to the peeling or separation of the LED chip before transfer. do.

1 is a conceptual diagram for explaining an LED chip transfer method according to an embodiment of the present invention.
FIG. 2 is a graph of expansion magnification according to the content of a photoactive agent in the photosensitive resin shown in FIG. 1 .
3 is a photograph showing the expansion state of the photosensitive resin applied to the LED chip transfer according to the embodiment of the present invention.
4 is a schematic diagram of a transfer device using an LED chip photosensitive resin according to an embodiment of the present invention.
5 is an enlarged photograph of a structure in which an actual LED chip is embedded in a resin according to the implementation schematic diagram of FIG. 4 .
6 shows an LED chip transfer method according to an embodiment of the present invention.
7 is a flowchart illustrating a method of manufacturing a display device according to an embodiment of the present invention.
8 is a diagram showing chips formed on each wafer according to an embodiment of the present invention.
9 is a process diagram of growing each Epi on each wafer according to an embodiment of the present invention.
10 is a process diagram of etching each chip formed on each wafer in a single chip unit according to an embodiment of the present invention.
11 is a process diagram of transferring the etched chip of FIG. 10 from a wafer to a first carrier substrate;
12 is a process diagram of removing a wafer using an LLO technique.
13 to 16 are process diagrams for explaining a process ( S160 ) of selectively transferring the chip array shown in FIG. 7 from a first carrier substrate to a second carrier substrate.
FIG. 17 shows a process ( S170 ) of transferring the LED chip array from the second carrier substrate of FIG. 16 to the display panel.

In the description of the embodiment, in the case where it is described as being formed on "above (above) or under (below)" of each component, the upper (above) or lower (below) two components are in direct contact with each other or one or more other components disposed between two components.

In addition, when expressed as "upper (upper) or lower (lower)", the meaning of not only an upper direction but also a lower direction based on one component may be included.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not fully reflect the actual size.

The chip, CSP, LED pixel CSP, and LED sub-pixel CSP used in the present invention may be defined as follows.

A chip is a concept including an LED chip, an RGB chip, an R chip, a G chip, a B chip, a mini LED chip, and a micro LED chip. Hereinafter, for convenience of description, 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 the R chip, the G chip, or the B chip.

A chip scale package (CSP) is a package that has recently received a lot of attention in the development of a single chip package, and refers to a single chip package having a semiconductor/package area ratio of 80% or more.

LED pixel CSP refers to a single package in which one LED pixel is CSP packaged by using Red LED, Green LED, and Blue LED as one pixel unit.

The LED sub-pixel CSP refers to a single package in which each of Red LED, Green LED, and Blue LED is used as one sub-pixel unit and CSP is packaged in one LED sub-pixel unit.

A light emitting body formed on a wafer may be defined as an LED chip.

1 is a conceptual diagram for explaining an LED chip transfer method according to an embodiment of the present invention.

The present invention utilizes the degradation properties and expandability of a photoactive agent.

When the base resin is irradiated with UV, a photoreaction occurs in the internal novolak resin and photoactivator to generate acid. This acid is liquid and when the wafer is placed on the hop plate and temperature is applied, only the UV-irradiated area expands. , expansion occurs when the volume of acid trapped inside the PR increases rapidly due to heat.

Here, by adding a photoactivator to increase the expansion power of the base resin to enable the transfer of the LED chip, the acid amount increases and the expansion power of the resin is increased to block the cause of the transfer failure.

Figure 1 (A) is a schematic diagram of the degree of expansion of the photosensitive resin by UV irradiation and heating in the case where the photoactive agent content is relatively small, and Figure 1 (B) is UV irradiation and heating in the case where the photoactive agent content is relatively high. The degree of expansion of the photosensitive resin by

The photosensitive resin of the present invention is made of a photosensitive resin in which a base resin, an organic solvent, and a photoactive agent are mixed, and the photosensitive resin is expanded by heat after exposure using the expandability of the photoactive agent, and the LED adhered to the photosensitive resin The LED chip can be transferred to the substrate by breaking or canceling the adhesive force of the chip.

The base resin may be selected from one or more of a phenol resin, an epoxy resin, a UV resin, a polyester resin, a polyurethane resin, or an acrylic resin, and as a preferred embodiment, a novolak resin among phenolic resins may be applied.

The organic solvent (solvent) may be selected from one or more solvents of alcohols, petroleum substances, aromatic solvents, ketones, glycol ethers, acetates, and DMCs, and in a preferred embodiment, acetate, acetone or PGMEA is applied. can

The photoactive agent refers to a material in the generic sense that refers to any one of a photoacid generator (PAG), a photoactive compound (PAC), a photoinitiator, a photosensitive compound, or a photoactive compound.

Photoactivators are Oxime-ester-based, s-Triazine-based, and Phosphineoxide-based photoinitiators, and a PAC material composed of at least one of them may be used, and a preferred embodiment of the present invention is 2-diazo-1-naph among ester-based materials. Ester compounds of ton-5-sulfonic acid chloride may be applied.

Figure 1 (A) is a case of a photosensitive resin synthesized in an amount of 2 wt% or less of a photoactive agent, (B) is a case of a photosensitive resin synthesized in an amount exceeding 6 wt% of a photoactive agent.

The photosensitive resins 102 and 103 are coated on the substrate 101, and a mask 105 is placed on the upper side thereof to irradiate UV.

The photosensitive resins 102 and 103 expand in the area irradiated with UV, and the photosensitive resins 102 and 103 do not expand in the area where UV is not irradiated.

That is, the adhesive force of the LED chip attached to the photosensitive resins 102 and 103 is zeroed according to the region of the presence or absence of UV irradiation according to the mask pattern, thereby selectively transferring the LED chip to another substrate.

However, in the case of (A), it is difficult to perform a complete function as a transfer because the expansion force of the photosensitive resin 102' is weak. It has enough expansive force to allow the transfer of

In the end, a significant amount of a photoactivator solution is mixed with the photosensitive resin to form an exposed area by UV irradiation, and heat is applied to the exposed area to cause the photosensitive resin in the exposed area to expand, so that the LED chip adhered to the exposed area. It is possible to peel off the LED chip or to transfer the LED chip onto another substrate. possible.

FIG. 2 is a graph of expansion magnification according to the content of a photoactive agent in the photosensitive resin shown in FIG. 1 .

2 is a graph showing the results of experimentally verifying the content of the photoactive agent in the photosensitive resin and the expansion ratio of the photosensitive resin.

The results of the graph shown in FIG. 2 are shown in a table as follows, which shows the relative values when heat is applied at the same UV irradiation amount and the same temperature.

PAC content
(wt%) One 2 3 4 5 6 7 10 expansion factor
(ship) 1.2 1.3 1.6 1.8 3.1 5.6 5.8 6.0

It can be seen that the slope value forms a steep slope when the PAC content is 4 to 6 wt%, and it can be seen that the expansion force of the maximum efficiency value according to the PAC content is within this range.

As a result, when the PAC content contains 4 to 6 wt%, the expansion ratio of the photosensitive resin has an expansion power of 1.8 to 5.6 times, and this expansion power is a physical that can be separated, that is, completely transferred by zeroing the adhesive force of the attached LED chip. value can be seen.

When the PAC content is 10 wt% or more, it appears that the expansion factor converges to 6.0 times, therefore, it can be seen that the expansion for LED chip transfer is made when the PAC content is 4 wt% or more.

However, looking at the expansion ratio alone, there is no significant difference in the expansion ratio at 6 wt% or more, but when the PAC content is 6 wt% or more, i.e., 12.7 wt%, as a result, the defect rate is significantly reduced.

This decrease in the defect rate is because the density (or density) of the photosensitive resin increases as the PAC content increases, and it can be confirmed through repeated experiments.

In fact, compared to 4 to 6 wt% of PAC content, 12.7 wt% increases the density by 20%, and this increase in density helps to minimize the transfer defect of the LED chip during expansion transfer.

The photosensitive resin of the present invention may further include a solvent (acetone), the base resin is 30 to 35 wt%, the organic solvent is 45 to 50 wt%, the solvent is 5 to 10 wt%, and the photoactive agent is 10 to 15 wt% It is preferable that it is a mixed resin prepared by mixing %.

In the photosensitive resin of the present invention, a filler capable of increasing the resin's rigidity may be further added, and ultrapure water (DI Water) serving as an auxiliary to improve the foaming performance may be further added.

The filler may be selected from SiOF series, SiOF2 series, SiOF3 series, and the like, and as a preferred embodiment, SiOF3 series fillers having a size of 3 μm may be used.

The filler is 0.1wt% to 10wt%, and ultrapure water can be mixed in 0.1wt% to 10wt%.

3 is a photograph showing the expansion state of the transfer resin applied to the LED chip transfer according to the embodiment of the present invention.

The photosensitive resin applied to the present invention may be a naphtoquinonediazide-novolac resin.

When 4 wt% or more of a photoactive activator is mixed with a photosensitive resin and irradiated with light, it is photodegraded to form highly reactive ketene. A positive image 104 is formed according to the ascending reaction mechanism.

In the photograph of FIG. 3 , the upper left photograph is the photosensitive resin photograph 103 before UV irradiation, and the upper right photograph is a photograph in which a positive image 104 is formed by UV irradiation.

The lower photo is an enlarged photo of a positive image, that is, a portion where the expansion region 103' is formed by irradiating UV.

It is possible to expand a specific position through the patterned mask, and the expansion region can be implemented to have the maximum effective expansion ratio by calculating the optimal mixing ratio of the photoactive agent, and only the photosensitive resin applied to the embodiment of the present invention The expansion force by the heat can perform the role of peeling or transferring the LED chip by breaking the adhesive force of the LED chip.

Based on FIGS. 1 to 3 , how the transfer process is actually performed will be described in detail with reference to FIG. 6 , and the transfer process from the wafer to the display panel will be described in more detail with reference to FIGS. 7 to 17 .

In particular, the structure of the transfer apparatus according to the embodiment of the present invention will be described again with reference to FIGS. 4 and 5 .

4 is a schematic diagram of a transfer device using an LED chip photosensitive resin according to an embodiment of the present invention.

Referring to FIG. 4 , the LED chip transfer device using the LED chip photosensitive resin according to the embodiment of the present invention is formed on the substrate 101 and the substrate 101, and a specific area is exposed by UV irradiation to form a photodegradation layer. and a photosensitive resin layer 103 made of a resin that expands at a predetermined temperature.

The LED chip 100 is disposed on the photosensitive resin layer 103 by a predetermined adhesive force of the photosensitive resin layer.

In the case of (A), the LED chip 100 is disposed on the upper surface of the photosensitive resin layer 103 , and in the case of (B), the LED chip 100 is embedded in the photosensitive resin layer 103 . looks like

In the present invention, in order to prevent the LED chip 100 from being easily separated or separated from the substrate, the structure of (A) is improved from the structure of (B).

The lower portion of the LED chip 100 is embedded in the photosensitive resin layer 103 to have a clip-up structure, so that the slope of the LED chip 100 is formed by the clip-up structure of the photosensitive resin layer 103 . A structure held by the resin can be prevented from being easily detached or peeled off from the substrate before transfer.

In this state, UV is applied to form a photodegradation layer, and when a predetermined heat is applied to the photodegradation layer, the photodegradation layer expands, and the adhesive force of the LED chip located in the photodegradation layer is offset, so that the LED chip can be peeled or transferred.

5 shows an enlarged photograph of a structure in which an actual LED chip is embedded in a resin according to the implementation schematic diagram of FIG. 4 .

6 shows an LED chip transfer method according to an embodiment of the present invention.

As shown in FIG. 6 , the LED chip transfer apparatus according to the present invention may include a substrate 101 , a photosensitive resin layer 103 , and LED chips 100 and 100 ′.

The LED chips 100 and 100' may mean an RGB LED chip, an R LED chip, a G LED chip, a B LED chip, and a CSP (Chip Scale Package), and the LED chip pixel CSP is a Red LED, a Green LED, and a Blue LED. may mean a single package in which one LED pixel is CSP packaged by using as one pixel unit, and the LED sub-pixel CSP is one LED sub-pixel by using each of Red LED, Green LED, and Blue LED as one sub-pixel unit. It may mean a single package packaged as a CSP unit.

The substrate 101 may be made of any one of glass, quartz, synthetic quartz, and metal, and the material is not particularly limited.

The photosensitive resin layer 103 may be a resin material containing 4 wt% or more of the photoactive agent, and as described above, the content of the photoactive agent may be set to 10 wt% or more, preferably 12.7 wt%, in order to increase the defect rate by increasing the density. will be.

A process of peeling or transferring the LED chips 100 and 100' at a specific position will be described with reference to FIG. 6 .

Referring to FIG. 6A , a photosensitive resin layer 103 is formed on a substrate 101 , and LED chips 100 and 100 ′ are disposed or transferred (from another substrate) on the photosensitive resin layer 103 . (meaning the transcription of) is formed.

Referring to FIG. 6B , a mask 105 to form a pattern is disposed on the back side of the substrate 101 , and UV is irradiated through the mask 105 .

The mask 105 and the photosensitive resin region exposed by UV irradiation are exposed by light as shown.

By the mask 105 and UV irradiation, the photosensitive resin has an exposed area and an unexposed area.

Referring to FIG. 6C , when heat is applied from the back side of the substrate 101 to reach a predetermined temperature, the exposure area in the photosensitive resin layer 103 expands and the volume expands, and the volume expands. The expansion region 103 ′ zeroes the adhesive force of the LED chip 100 .

Conversely, since there is no expansion in the unexposed region 103 , the adhesive force of the LED chip 100 is maintained as it is.

Referring to FIG. 6D , the LED chip 100 attached to the corresponding position is peeled off, and if there is a target substrate on the opposite side, it may be transferred to the target substrate and may be transferred to another position (not the expansion region). The LED chip 100' adhered to the position) is placed on the substrate as it is, and it is possible to selectively peel or transfer the LED chip as needed.

Here, the photosensitive resin is fundamentally different from the use of the photosensitive resin in a semiconductor process such as pattern formation in that there is only an exposure process by UV and an expansion process by heat and no development process is performed.

Hereinafter, a transfer method to a display panel using the above-described LED chip transfer apparatus will be described in detail with reference to FIGS. 7 to 17 .

7 is a flowchart illustrating a method of manufacturing a display device according to an embodiment of the present invention.

Referring to FIG. 7 , in the method of manufacturing a display device according to an embodiment of the present invention, each of a plurality of chips is formed on each wafer ( S110 ), and each chip is etched on each wafer by one chip ( S110 ). Etching) step (S120), attaching the chip array of each wafer separated in chip unit to the first carrier substrate (S130), removing the wafer by LLO (Laser Lift Off) process (S140), Preparing the second carrier substrate (S150), selectively transferring the chip array from the first carrier substrate to the second carrier substrate (S160), sequentially transferring the chip array selectively transferred to the second carrier substrate to the display panel It includes a step of transferring (S170) and a step of removing the second carrier substrate (S180).

Specific examples are as follows.

Before step S130, a step of preparing a photoactive agent solution (solution) may be added.

A photoactivator solution is prepared by mixing acetone (Acetone) and photoactive activator (PAC).

The photosensitive resin layer is prepared by mixing a base resin and a PAC solution.

In step S130, the prepared photosensitive resin and the photosensitive transfer resin layer of the PAC solution are coated on the first carrier substrate by a spin coating process.

The coated photosensitive transfer resin layer was first soft cured at 105 degrees for 90 seconds, and second soft cured at 105 degrees for 60 seconds again.

In step S130, heat is applied to the prepared photosensitive transfer resin layer at 105 degrees for 60 seconds to transfer the LED chip on the wafer to the first carrier substrate.

In step S150, a second carrier substrate is prepared by applying an EMC (Expandable Micro-Capsule) adhesive layer in which a foam and an adhesive liquid are mixed on a glass substrate, or a heat release film is attached.

In step S160, the second carrier substrate is bonded to the opposite side of the first carrier substrate, aligned using a mask aligner, irradiated with UV of 2,000 mJ calorie, and heated at 100 degrees for 20 seconds on the first carrier substrate. The photosensitive resin layer is heated to expand, and at this time, the first carrier substrate is separated, and the transfer of the LED chip to the second carrier substrate is completed.

In steps S170 and S180, a TFT array is prepared, a solder paste is applied, and the second carrier substrate and the TFT array are bonded.

The second carrier substrate is separated by heating at 200 degrees for 90 seconds to foam the foam of the EMC adhesive layer of the second carrier substrate, and the LED chip is transferred on the display substrate (TFT array).

8 is a diagram showing chips formed on each wafer according to an embodiment of the present invention.

As shown in FIG. 8 , the embodiment of the present invention describes three wafers each having an R chip, a G chip, and a B chip as an example, but is not limited thereto.

Referring to FIG. 8 , a plurality of light emitting devices 11R, 11G, and 11B emitting light of the same wavelength band are formed on each of the wafers 10R, 10G, and 10B.

Here, the light emitting devices 11R, 11G, and 11B may be light emitting chips emitting red, green, and blue light.

The plurality of light emitting devices 11R, 11G, and 11B may be arranged at equal intervals along a plurality of rows and columns on each wafer 10R, 10G, and 10B.

Since the light emitting devices 11R, 11G, and 11B arranged at equal intervals are transferred to the display panel thereafter in the row or column direction, the manufacturing cost of the light emitting device can be reduced by efficiently utilizing the entire area of a relatively expensive wafer.

Meanwhile, after forming a plurality of chips on each of the wafers 10R, 10G, and 10B, the wafers may be separated for each chip through an etching process for each chip.

It is preferable that the pitch W between the chips formed on each of the wafers 10R, 10G, and 10B is the same as the pitch between the chips formed on the display panel or is set as a multiple of a proportional constant of a predetermined value.

This may facilitate the transfer when selectively transferring the chips from the second carrier substrate to the display panel in a matrix unit, which will be described later.

9 is a process diagram of growing each Epi on each wafer according to an embodiment of the present invention.

Referring to FIG. 9 , epis 11R, 11G, and 11B emitting a predetermined light are grown on one surface of each of the three wafers 10R, 10G, and 10B.

Here, the wafers 10R, 10G, and 10B may be one of sapphire (Al2O3), silicon, gallium arsenide (GaAs), gallium nitride (GaN), and zinc nitride (ZnN). However, the present invention is not limited thereto, and any substrate that can be used as a wafer may be used.

Forming the pads 14r, 14g, 14b on the grown epi (11R, 11G, 11B), respectively, and protecting the epi (11R, 11G, 11B) and the pad (14r, 14g, 14b) passivation (Passivation) A layer 13 is formed.

Here, the pads 14r, 14g, and 14b are not expanded and may have the size and shape of a general pad.

When forming the protective layer 13, it is preferable to form the pads 14r, 14g, and 14b so that they are exposed to the outside of the protective layer 13 in order to expand the area of the pad thereafter.

9 is a cross-sectional view of the AA Section and the BB Section in FIG. 8, respectively. Preferably, a pair of (+), (-) electrodes per chip are formed under the Epi layer, and the electrodes are based on the AA section. Of course, it can be formed up and down, and it is also possible to form left and right if necessary.

The light emitting bodies formed on the wafers 10R, 10G, and 10B are in a state of being electrically separated in units of chips, and in the present invention, they are referred to as LED chips, and after etching for each chip, the first carrier substrate from the wafers 10R, 10G, and 10B is transcribed into

10 is a process diagram of etching each chip formed on each wafer in a single chip unit according to an embodiment of the present invention.

Referring to FIG. 10, as shown in FIG. 9, epis 11R, 11G, 11B and pads 14r, 14g, and 14b are formed on wafers 10B, 10G, and 10B, and a protective layer 13 is applied to each chip. A plurality of physically separated chips 100R, 100G, and 100B are formed by etching. Here, each chip and the protective layer 13 surrounding the chip will be referred to as a chip in the present specification. Of course, each chip and the protective layer 13 surrounding the chip may also be referred to as a pixel CSP or a sub-pixel CSP.

Here, in the etching process for each chip 100R, 100G, and 100B, wet or dry etching may be applied, and the shape of the LED chip is defined by etching, in which case the wafers 10B, 10G, and 10B are will remain as it is.

In the drawings below, one chip 100R, 100G, and 100B is illustrated as the chips 100R, 100G, and 100B formed in FIG. 8 , but is not limited thereto. In FIG. 6 , the chips 100R, 100G, and 100B are etched in the row and column directions. It may be a (100R, 100G, 100B) array.

Each of the chips 100R, 100G, and 100B may have a flip-chip structure that does not require wires.

Electrical connection is possible with the pads 14r, 14g, and 14b instead of wires, and each of the chips 100R, 100G, and 100B emits light of various colors according to an external control signal through the pads 14r, 14g, and 14b. can

In addition, in the present invention, each of the chips 100R, 100G, and 100B may be packaged into a new concept small package manufactured in the form of a CSP by configuring sub-pixels for each R, G, and B, respectively.

The R chip 100R, the G chip 100G, and the B chip 100B may constitute one light emitting device or a light emitting body.

By attaching a plurality of each of the chips 100R, 100G, and 100B to the first carrier substrate in the row and column directions, a pre-process for transferring the chip array may be performed, and from the first carrier substrate to the second carrier substrate. After selectively transferring, the chip array arranged on the second carrier substrate may be sequentially transferred to a display panel to be described later.

As shown in FIG. 10 , a process of removing the wafer is performed by attaching chip arrays etched in the form of chips 100R, 100G, and 100B to a carrier substrate on each of the wafers 10B, 10G, and 10B, and thereafter, the first carrier substrate A process of sequentially selective transfer to the second carrier substrate and sequentially selective transfer to the display panel will be described.

The following drawings are described based on the row (horizontal) arrangement in the matrix-arranged chip array on the wafer of FIG. 8 .

11 is a process diagram of transferring the etched chip of FIG. 10 from a wafer to a first carrier substrate, and FIG. 12 is a process diagram of removing the wafer using an LLO technique.

11 and 12 are processes for removing the wafers 10R, 10G, and 10B to transfer the etched chip to the first carrier substrate 210R.

The first carrier substrate 210R may have the same configuration as the transfer device of FIG. 4 .

Referring to FIG. 11 , after the chips are separated in the matrix direction by etching (as shown in FIG. 10 ), the first carrier substrates 210R, 210G, and 210B are applied to the LED chips in the opposite direction of the wafers 10R, 10G, and 10B. (100R, 100G, 100B).

That is, the first carrier substrates 210R, 210G, and 210B are attached to the pads 14r, 14g, and 14b of the chips 100R, 100G, and 100B.

The first carrier substrates 210R, 210G, and 210B include substrates 211R, 211G, and 211B and photosensitive transfer resin layers 213R, 213G, and 213B.

The substrates 211R, 211G, and 211B may be made of any one of glass, quartz, synthetic quartz, and metal, and the material is not particularly limited.

The photosensitive resin layers 213R, 213G and 213B are made of a resin containing 4 wt% or more of a photoactive agent.

12, when the wafers 10R, 10G, and 10B are removed by the LLO (Laser Lift Off) process in the same state as in FIG. 11 , the LED chips 100R, 100G, and 100B are formed on the first carrier substrate 210R, It is placed in a state attached to 210G and 210B, and at this time, the directions of the chips 100R, 100G, and 100B are opposite to each other, and the light emitting body is exposed.

The first carrier substrates 210R, 210G, and 210B include a first carrier substrate 210R in which an R LED chip array is formed, a first carrier substrate 210G in which a G LED chip array is formed, and a first first carrier substrate in which an array of B LED chips is formed. A carrier substrate 210B may be included.

13 to 16 are exemplary views for explaining a process of selectively transferring the chip array shown in FIG. 7 from a first carrier substrate to a second carrier substrate.

13 to 16 are described based on only one LED chip among the RGB LED chips shown in FIGS. 9 to 12 .

Referring to FIG. 13 , the second carrier substrate 220 is disposed on the first carrier substrate 210 on which the LED chip array 100 is formed.

The EMC adhesive layer 223 of the second carrier substrate 220 is brought into contact on the LED chips 100 to be attached to each other.

Here, the second carrier substrate 220 may be formed of a glass substrate 221 and an EMC adhesive layer 223 including a foam 225 .

Foam 225 may be a micro-scale encapsulated foam material having foaming properties at a predetermined temperature.

The EMC (Expandable Micro-Capsule) adhesive layer 223 may be a resin in which the foam 225 and the adhesive liquid are mixed.

Referring to FIG. 14 , in a state in which the first carrier substrate 210 and the second carrier substrate 220 face each other with the LED chip 100 interposed therebetween, as shown in FIG. 13 , the A mask 215 is disposed on the back surface of the glass substrate 211 .

The mask 215 may be a pre-patterned mask.

UV is irradiated while the mask 215 is disposed.

Only a specific region of the photosensitive transfer resin layer 213 may be exposed by the mask 215 pattern and UV irradiation.

Here, the 'exposure' may have an exposure degree adjusted according to the control of the UV exposure energy.

The controlled exposure portion of the photosensitive resin according to the amount of UV irradiation may be referred to as a photo-induced degradation layer.

The photodegradation layer can selectively transfer only the LED chip at the corresponding position through the expansion of the photosensitive resin and the zeroing of the adhesive force of the LED chip as heat is applied.

Referring to FIG. 15 , heat is applied to the upper portion of the first carrier substrate 210 .

In this case, heat may mean an expandable temperature of the photosensitive resin layer 213 .

When heat is applied to the first carrier substrate 210 so that the photosensitive resin layer 213 reaches a temperature at which it can expand, the photosensitive resin layer 213 becomes the photosensitive resin layer 213' in which the volume is expanded. A possible position may be a region in which the photodegradation layer progressed in FIG. 14 exists.

The volume-expanded photosensitive resin layer 213' increases in size and pushes the LED chip 100 by the pressure (expansion force) when the volume expands, thereby zeroing the adhesive force of the LED chip 100, The LED chip 100 adhered to the corresponding position is peeled (or transferred) to a state in which it can be transferred to the second carrier substrate 220 .

Referring to FIG. 16 , it can be seen that only a specific LED chip 100 is selectively peeled off and transferred from the first carrier substrate 210 to the second carrier substrate 220 .

17 is a cross-sectional process diagram illustrating a process in which the LED chip array is transferred from the second carrier substrate 220 to the display panel 300 .

Referring to FIG. 17A , solder paste 33 is applied on the plurality of pads 31 of the display panel 300 .

A TFT array substrate 400 may be disposed under the display panel 300 .

Here, the solder paste 33 may be applied on the pads 31-SP1 to 31-SP4 in rows 1 to 4, or the solder paste 33 is applied only to the pad at the position where the LED chip 100 is selectively transferred. It can be applied selectively.

The solder paste 33 may be applied on the plurality of pads 31 of the display panel 300 through various methods such as screen printing, dispensing, jetting, and the like.

Next, referring to FIG. 17B , the LED chip array 100 attached to the second carrier substrate 220 is disposed on the display panel 300 , and the pad of the LED chip array 100 is displayed. The solder pastes 33-SP1 to 33-SP4 applied on the pad 31 of the panel 300 are arranged.

Next, referring to FIG. 17C , heat is applied from an upper portion of the second carrier substrate 220 .

In this case, the heat means a temperature at which the foam 225 can be foamed.

The foam 225 loses the adhesive force between the LED chip 100 and the second carrier substrate 220 while pushing the EMC adhesive layer 223 including the adhesive solution impregnated therein with a constant pressure, and the volume of the foam 225 is expanded by heat. The LED chip 100 positioned on the layer 223 may be transferred onto the display panel 300 .

By repeatedly performing these processes, it becomes possible to sequentially transfer the R, G, and B LED chips sequentially on the display panel 300 in order of time intervals.

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiment has been mainly described in the above, 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 to the above in the range that does not depart from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications not illustrated are possible. For example, each component specifically shown in the embodiment can be implemented with 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.

10R, 10G, 10B: Wafer
100, 100R, 100G, 100B: LED chip
210, 210R, 210G, 210B: first carrier substrate
220, 220R, 220G, 220B: second carrier substrate
300: display panel
400: TFT array substrate

Claims (6)

Board; and
A photosensitive resin layer formed on the substrate, a specific region is exposed by UV irradiation to form a photodegradation layer, and a photosensitive resin layer made of a photosensitive resin in which the photodegradation layer expands at a predetermined temperature;
An LED chip is disposed on the photosensitive resin layer, and a lower portion of the LED chip is placed in a state embedded in the photosensitive resin layer by a clip-up structure,
The photodegradation layer is expanded by applying a predetermined heat, and the adhesive force of the LED chip located in the photodegradation layer is canceled so that the LED chip is peeled or transferred,
In the photosensitive resin, a specific area is exposed by a mask and UV irradiation to form a photodegradation layer, and by applying a predetermined heat, the photodegradation layer is expanded to selectively transfer only the LED chip located in the photodegradation layer. LED using a photosensitive resin chip transfer device. According to claim 1,
The photosensitive resin is prepared by mixing a base resin, an organic solvent and a photoactive agent, an LED chip transfer device using a photosensitive resin. delete According to claim 1,
The photosensitive resin further comprises a solvent, the LED chip transfer device using the photosensitive resin. According to claim 1,
A filler for reinforcing the adhesive force of the LED chip is added to the photosensitive resin, an LED chip transfer device using a photosensitive resin. Board; and
A photosensitive resin layer formed on the substrate, a specific region is exposed by UV irradiation to form a photodegradation layer, and a photosensitive resin layer made of a photosensitive resin in which the photodegradation layer expands at a predetermined temperature;
An LED chip is disposed on the photosensitive resin layer, and a lower portion of the LED chip is placed in a state embedded in the photosensitive resin layer by a clip-up structure,
The photodegradation layer is expanded by applying a predetermined heat, and the adhesive force of the LED chip located in the photodegradation layer is canceled so that the LED chip is peeled or transferred,
An LED chip transfer device using a photosensitive resin, in which ultrapure water (DI water) is added to the photosensitive resin.

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