KR102189680B1 - Micro LED manufacturing and selective transferring method - Google Patents

Abstract

The present invention relates to a method for selectively transferring micro LEDs, and more particularly, to a manufacturing process for manufacturing a micro LED, and an LLO for separating a chip from a micro LED manufactured through the manufacturing process of a micro LED using a conventional laser. A micro LED that can be easily transferred to a target device using a material whose adhesive strength varies according to temperature conditions after chip separation by CLO (Chemical Lift Off) method from the substrate using an etching solution by removing the laser lift off method. It relates to a selective transfer method.
The micro LED selective transfer method according to the present invention is a large-area processing compared to the conventional transfer method in which the micro LED is separated from the substrate using a femtosecond laser and then selectively transferred to the target device, the adhesive force of the temperature-variable adhesive sheet is adjusted, and the micro LED It can be transferred very easily, and since it does not use a laser, there is an advantage of less damage to the adhesive sheet and micro LED.

Description

Micro LED manufacturing and selective transferring method

The present invention relates to a method for selectively transferring micro LEDs, and more particularly, to a manufacturing process for manufacturing a micro LED, and an LLO for separating a chip from a micro LED manufactured through the manufacturing process of a micro LED using a conventional laser. A micro LED that can be easily transferred to a target device using a material whose adhesive strength varies according to temperature conditions after chip separation by CLO (Chemical Lift Off) method from the substrate using an etching solution by removing the laser lift off method. It relates to a selective transfer method.

Micro LED is emerging as a next-generation display light source, but research is needed to overcome technical difficulties such as RGB pixel process, TFT technology integration, and productivity improvement. High-speed response, high-definition, low-power consumption 4K UHD or higher AMLED for wearable displays (Active Matrix) Display development requires 2000ppi pixels.

For this, a very small pixel size of 10 micrometers or less is required, but as the micro LED size decreases, a selective transfer method capable of separating the light emitting layer from the wafer and accurately aligning it with the target device is required.

In addition, conventional micro LEDs require expensive laser equipment in the process of separating the substrate to make the chip small and thin, and in the process of separating the substrate through wet etching, a complicated process of erecting a pillar through a separate process is required. In addition, since a method of transferring one or tens to hundreds of units is applied to a small target device, there is a problem that expensive equipment is required and the process is complicated.

In addition, the conventional micro LED selective transfer method using a femtosecond laser and an environmental condition variable adhesive sheet in which adhesive strength occurs or disappears depending on environmental conditions cannot be controlled due to the burning of the adhesive sheet during large-area processing. The adhesion of the sheet is maintained and there is a problem in that the micro LED is cracked or damaged when the micro LED is separated.

Republic of Korea Patent Publication 10-2018-0115584 Republic of Korea Patent Publication 10-2015-0073526 Republic of Korea Patent Publication 10-2004-0104232 Korean Patent Registration 10-1342577

The present invention is to solve the conventional problem as described above, avoiding the method of selectively transferring micro LEDs using a conventional femtosecond laser, and selectively using only the desired micro LEDs without cracking and damage using a CLO method and a PET mask. Its purpose is to provide a selective transfer method of micro LEDs that can be easily transferred by means of.

In order to achieve the above object, a method for selectively transferring a micro LED according to an embodiment of the present invention includes forming a semiconductor structure on a substrate, and exposing a part of the semiconductor layer inside the semiconductor structure to the outside. A micro LED manufacturing step of manufacturing a micro LED including etching a part of the structure; A preliminary separation step of separating a predetermined portion from the substrate using a photoresist, an exposure apparatus, and an etching solution of only the micro LED selected primarily among the micro LEDs on the substrate; A complete separation step of attaching and fixing the micro LEDs on the substrate to a temperature-variable pressure-sensitive adhesive sheet in which adhesive force occurs, weakens or disappears according to temperature conditions, and then completely separates only the firstly selected micro LEDs from the substrate; A transfer step of transferring the micro LEDs moved from the substrate to the temperature-variable adhesive sheet to a target device, and after the transfer step, secondary and third micro LEDs remaining on the substrate after the complete separation step It characterized in that it further comprises a repeating step of repeating the preliminary separation step, the complete separation step, and the transfer step so that the micro LED selected as a car can be sequentially separated from the substrate and sequentially transferred to the target device. To do.

The preliminary separation step of the selection transfer method of micro LEDs according to an embodiment of the present invention includes a coating step of applying a photoresist to the substrate and the micro LEDs so as to surround all micro LEDs on the substrate, and one of micro LEDs. An exposure step of selectively exposing only the remaining areas except for a specific area of the photoresist surrounding the selected micro LED, a first removal step of removing a specific area of the photoresist surrounding the first selected micro LED from among the micro LEDs, and etching An etching step of separating a predetermined portion of the micro LED selected from the micro LEDs from the substrate using a solution, and removing the remaining area of the photoresist surrounding the remaining micro LEDs other than the micro LED selected primarily from the micro LEDs It characterized in that it comprises two removing steps.

A p-type electrode and an n-type electrode on the top of the semiconductor structure between the etching step and the second removing step of the micro LED manufacturing step or the preliminary separation step of the micro LED selection transfer method according to an embodiment of the present invention An electrode portion forming step of forming an electrode portion including, and a protective film forming step of covering an upper portion of the semiconductor structure excluding the electrode portion with a protective film to protect the upper portion of the semiconductor structure.

The temperature-variable pressure-sensitive adhesive sheet applied in the complete separation step of the selective transfer method of the micro LED according to an embodiment of the present invention is characterized in that adhesion occurs, weakens, or disappears according to temperature conditions.

On the other hand, the selective transfer method of a micro LED according to another embodiment of the present invention comprises the steps of forming a semiconductor structure on a substrate and etching a part of the semiconductor structure so that a part of the semiconductor layer inside the semiconductor structure is exposed to the outside. And, an electrode part forming step of forming an electrode part on the upper part of the semiconductor structure, and a protective film forming step of covering an upper part of the semiconductor structure excluding the electrode part with a protective film so as to protect the upper part of the semiconductor structure. A micro LED manufacturing step; A preliminary separation step of separating all the micro LEDs on the substrate from the substrate by using an etching solution; Using a temperature-variable pressure-sensitive adhesive sheet that generates, weakens, or disappears according to temperature conditions, and a mask made of PET and formed in a specific pattern, only the micro-LEDs selected primarily among the micro-LEDs on the substrate are adhered to the temperature-variable pressure-sensitive adhesive sheet and A complete separation step of completely separating only the firstly selected micro LED from the substrate after fixing; A transfer step of transferring the micro LEDs moved from the substrate to the temperature-variable adhesive sheet to a target device, and after the transfer step, secondary and third micro LEDs remaining on the substrate after the complete separation step It characterized in that it further comprises a repeating step of repeating the complete separation step and the transfer step so that the micro LED selected as a vehicle can be sequentially separated from the substrate and sequentially transferred to the target device.

The complete separation step of the selection transfer method of the micro LED according to an embodiment of the present invention includes a thin film forming step of forming a PET thin film layer on a first temperature-variable adhesive sheet, and a position of the micro LED in which the PET thin film layer is first selected. A mask forming step of forming a PET mask by laser processing in a specific pattern corresponding to, a mask transfer step of transferring the mask to a second temperature-variable adhesive sheet, and a microscopic part separated from the substrate through the pre-separation step. Including a separation step of completely separating the micro LED from the substrate after the second temperature-variable adhesive sheet and the substrate are in close contact with each other to adhere and fix the LED on the second temperature-variable adhesive sheet excluding the mask. It is characterized.

The micro LED selective transfer method according to the present invention is a large-area processing compared to the conventional transfer method in which the micro LED is separated from the substrate using a femtosecond laser and then selectively transferred to the target device, the adhesive force of the temperature-variable adhesive sheet is adjusted, It can be transferred very easily, and since it does not use a laser, there is an advantage that there is little damage to the adhesive sheet and the micro LED.

1 to 13 are views showing a method of selectively transferring a micro LED according to a first embodiment of the present invention.
14 to 26 are views showing a method of selectively transferring a micro LED according to a second embodiment of the present invention.
27 to 38 are views showing a method of selectively transferring micro LEDs according to a third embodiment of the present invention.

Hereinafter, a method for selectively transferring a micro LED according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 to 13 illustrate a method of selectively transferring a micro LED according to a first embodiment of the present invention. 1 to 13, the method for selectively transferring a micro LED according to the first embodiment of the present invention includes a micro LED manufacturing step (S10), a preliminary separation step (S20), a complete separation step (S30), and It comprises a transfer step (S40).

Micro LED manufacturing step (S10) includes a semiconductor structure forming step of forming a semiconductor structure (hereinafter, micro LED 15) including a p-type semiconductor layer, an n-type semiconductor layer and an active layer on the substrate 11, and a micro LED (15) A micro LED 15 is manufactured including an etching step of forming a mesa structure by etching a part of the micro LED 15 to expose a part of the p-type semiconductor layer or the n-type semiconductor layer to the outside. .

For example, in the etching step, when the micro LED 15 grown on the substrate 11 is a micro LED 15 in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially stacked, a part of the n-type semiconductor layer is The p-type semiconductor layer and part of the active layer are removed to expose to the outside. After the etching step, a mesa structure in which the n-type semiconductor layer exposed to the outside of the micro LED 15 is positioned lower than the p-type semiconductor layer is formed.

The substrate 11 used in the micro LED manufacturing step (S10) may be a Si substrate or a GaAs substrate, and a Si substrate or a GaAs substrate may be used depending on the wavelength of light emitted from the micro LED 15 to be manufactured. You can choose. For example, when the wavelength of light emitted from the micro LED 15 to be manufactured is a short wavelength band of 550 nm or less, a Si substrate may be applied, and when a wavelength of 550 nm or more is a long wavelength band, a GaAs substrate may be applied.

In addition, the micro LED manufacturing step of the selective transfer method of the micro LED according to the first embodiment of the present invention does not include an electrode portion forming step for forming an electrode portion on a semiconductor structure, and a protective film forming step for forming a protective layer, As shown in FIGS. 4 and 5, forming an electrode portion and a protective film between the etching step S24 and the second removing step S25 of the preliminary separation step S20 was applied.

In the preliminary separation step (S20), only the micro LED 15A selected primarily among the micro LEDs 15 formed on the substrate 11 as shown in FIGS. 2 to 6 is a photoresist 21 and a photomask 22 , As a step of separating a certain portion from the substrate 11 using an exposure apparatus and an etching solution, a coating step (S21), an exposure step (S22), a first removal step (S23), an etching step (S24), and , And a second removing step (S25).

In the coating step (S21), the photoresist 21 is coated on the upper portion of the substrate 11 so as to surround all the micro LEDs 15 on the substrate 11.

The exposure step (S22) is a specific area of the photoresist 21 surrounding the micro LED 15A, which is primarily selected among the micro LEDs 15 using a photomask 22 and an exposure apparatus, as shown in FIG. Only the remaining areas except for (21A) are selectively exposed.

The photoresist 21 is inherently soluble in a special chemical or solution (KOH in the case of a Si substrate, HF in the case of a GaAs substrate), but the negative type becomes insoluble when exposed to light, and on the contrary, it is originally against a special chemical or solution. Although insoluble or positive type that changes to soluble when exposed to light can be applied, the former is applied in this embodiment, but the latter can be applied.

The first removing step (S23) removes a specific region 21A of the photoresist 21 surrounding the micro LED 15A that is primarily selected among the micro LEDs 15, that is, receives light by the photomask 22. The specific area 21A of the photoresist 21 is removed using a separate special chemical or solution to expose the firstly selected micro LED 15A to the outside. As the drug or solution applied in the first removal step (S23), Tetramethylammonium hydroxide, ethyl lactate and diacetone alcohol may be used.

The etching step (S24) is a step of separating a predetermined portion from the substrate 11 of the micro LEDs 15A, which are primarily selected among the micro LEDs 15, using an etching solution as shown in FIG. 4. After the whole is immersed in the etching solution, a portion of the first selected micro LED 15A is separated from the substrate 11 by etching the bonding portion between the firstly selected micro LED 15A and the substrate 11 by a CLO method.

Referring to FIG. 4, the firstly selected micro LED 15A is removed so that only about 15% of the bonding force with the substrate 11 remains or about 85% of the bonding force is removed through the etching step S24. Can be. At this time, the remaining micro LEDs 15 except for the firstly selected micro LED 15A are protected by the photoresist 21 so that the bonding force to the substrate 11 is not removed or weakened.

As the etching solution used in the etching step (S24), potassium hydroxide (KOH) or hydrofluoric acid (HF) can be applied depending on the type of substrate, and potassium hydroxide (KOH) is used when applying a Si substrate, and a GaAs substrate When applying, hydrofluoric acid (HF) is used.

In the second removing step (S25), the remaining areas of the photoresist 21 surrounding the remaining micro LEDs 15 other than the micro LED 15A selected primarily among the micro LEDs 15 are completely removed as shown in FIG. As a removing step, the remaining area of the photoresist 21 may be removed through acetone, oxygen plasma treatment, and 1-methyl-2-pyrrolidone (NMP).

After the second removal step (S25), as shown in FIG. 7, only a level of about 15% of the bonding force between the micro LED 15 and the substrate 11 in the previous etching step (S24) remains about 15% of the original bonding force. In this state, the etching step (S24) of removing the bonding force so that only about 5% of the bonding force between the micro LED 15 and the substrate 11 remains, may be repeated once more.

In addition, as shown in FIGS. 4 and 5, between the etching step S24 and the second removing step S25 of the preliminary separation step S20, an electrode part forming step and a protective film forming step may be further included.

The electrode part forming step is a step of forming the electrode part 13 on the top of the first selected micro LED 15 that is exposed to the outside through the first removing step (S23) of FIG. 3, such as ITO in the p-type semiconductor layer. A transparent electrode is formed, a p-type electrode is formed on the transparent electrode, and an n-type electrode is formed on the n-type semiconductor layer exposed to the outside in the etching step.

In the protective film forming step, a protective film is formed by wrapping the upper portion of the micro LED 15 excluding the electrode part 13 with a protective film so as to protect the upper portion of the micro LED 15.

In the micro LED manufacturing step (S10) of the micro LED selection transfer method according to the present embodiment, without forming the electrode part 13 on the micro LED 15, the etching step (S24) and the preliminary separation step (S20) 2 When etching by immersing the substrate 11 in the etching solution in the etching step (S24) by forming the electrode part 13 on the micro LED 15 between the removing steps (S25), the electrode part 13 It can be prevented from being damaged by.

In the complete separation step (S30), after attaching and fixing the micro LEDs 15 on the substrate 11 to the first temperature-variable pressure-sensitive adhesive sheet 31 where adhesive strength occurs, weakens or disappears according to temperature conditions, Only the LED 15A is completely separated from the substrate 11.

The complete separation step (S30) is a first temperature-variable adhesive by turning the substrate 11 over so that the micro LED 15 on the substrate 11 is in close contact with the first temperature-variable adhesive sheet 31 at room temperature as shown in FIG. In close contact with the sheet 31, as shown in FIG. 9, by generating adhesive force on the first temperature-variable pressure-sensitive adhesive sheet 31, the micro LED 15 is made to be adhered and fixed to the first temperature-variable pressure-sensitive adhesive sheet 31. 1 The temperature of the temperature-variable adhesive sheet 31 is adjusted, and the substrate 11 is separated from the first temperature-variable adhesive sheet 31.

The first temperature-variable adhesive sheet 31 applied in the complete separation step (S30) applies a cool-off type in which adhesive force occurs above the set reference temperature, and the adhesive force disappears below the set reference temperature, and the first temperature is variable. The first temperature-variable pressure-sensitive adhesive sheet 31 is heated to a level of room temperature so that the micro LED 15A in close contact with the pressure-sensitive adhesive sheet 31 is adhered and fixed to the first temperature-variable pressure-sensitive adhesive sheet 31.

The micro LED 15A, which is primarily selected through the complete separation step S30, is completely separated from the substrate 11 and is moved to the first temperature-variable adhesive sheet 31 at the same time.

The transfer step (S40) is a step of transferring the micro LED 15A moved from the substrate 11 to the first temperature-variable adhesive sheet 31 to the target device 40 as shown in FIGS. 10 to 13, It includes a first transfer step (S41) and a second transfer step (S42).

The first transfer step (S41) is a first temperature so that the micro LED (15A) on the first temperature-variable adhesive sheet 31 is in close contact with the second temperature-variable adhesive sheet 32 of another type as shown in FIG. Turn the variable pressure-sensitive adhesive sheet 31 in close contact with the second temperature-variable pressure-sensitive adhesive sheet 32, and move the micro-LED 15A to the second temperature-variable pressure-sensitive adhesive sheet 32 as shown in FIG. The first temperature-variable pressure-sensitive adhesive sheet 31 so that the adhesion of the first temperature-variable pressure-sensitive adhesive sheet 31 to (15A) is extinguished and the second temperature-variable pressure-sensitive adhesive sheet 32 to the micro LED (15A) can generate the adhesive force. ) And the temperature of the second temperature-variable adhesive sheet 32 are respectively controlled, and the first temperature-variable adhesive sheet 31 is separated from the second temperature-variable adhesive sheet 32.

The second temperature-variable pressure-sensitive adhesive sheet 32 applied in the first transfer step (S41) weakens or disappears above a set reference temperature (for example, at room temperature), and a warm-off in which adhesion occurs below the set reference temperature. Type is applied, and in the temperature adjustment step of the first transfer step (S41), the micro LED 15A in close contact with the second temperature-variable adhesive sheet 32 is attached and fixed to the second temperature-variable adhesive sheet 32. The 1 temperature-variable adhesive sheet and the second temperature-variable adhesive sheet 32 are cooled below a set reference temperature.

As shown in FIG. 11, the micro LED 15A of the first temperature-variable adhesive sheet 31 is completely moved to the second temperature-variable adhesive sheet 32 through the first transfer step (S41).

And, the second transfer step (S42) is a step of moving the micro LED (15A) moved to the second temperature-variable adhesive sheet 32 through the first transfer step (S41) to the target device 40, FIG. As shown in the second temperature-variable pressure-sensitive adhesive sheet 32 so that the electrode portion 13 of the micro LED 15A transferred to the second temperature-variable pressure-sensitive adhesive sheet 32 faces the bonding layer 41 of the target device 40 ( 32) is in close contact with the target device 40, and the temperature of the second temperature-variable pressure-sensitive adhesive sheet 32 is adjusted to extinguish the adhesive force of the second temperature-variable pressure-sensitive adhesive sheet 32 to the micro LED 15A. As shown in Fig. 13, by separating the second temperature-variable pressure-sensitive adhesive sheet 32 from the target device 40, the transfer process of the micro LED 15A selected primarily to the target device 40 is completed.

The bonding layer formed on the target device is for connecting the electrode part 13 of the firstly selected micro LED 15A to the circuit pattern formed on the target device and bonding it to the target device, and fine conductive particles are dispersed in the resin. , Anisotropic Conductive Film (ACF) or anisotropic conductive adhesive (ACA) in the form of a film in which conduction is performed only in the thickness direction when heating and pressing in the thickness direction can be applied. The conductive particles in the anisotropic conductive film or the anisotropic conductive adhesive may include nickel, carbon, solder balls, etc. having a particle size of several micrometers.

In the second transfer step (S42), the second temperature-variable adhesive sheet 32 so that the micro LED 15 in close contact with the bonding layer 41 of the target device 40 remains in the bonding layer 41 of the target device 40. ) Is heated above the set reference temperature or at room temperature.

The transfer step (S40) of the micro LED selection transfer method according to the present invention is divided into a first transfer step (S41) and a second transfer step (S42) through a complete separation step (S30). In the state that the electrode part 13 of the micro LED 15A moved to 31 is adhered and fixed to the first temperature-variable adhesive sheet 31, the electrode part 13 of the micro LED 15A is applied to the target device 40. ) Because it is impossible to bond to the bonding layer 41 of the second temperature-variable pressure-sensitive adhesive sheet from the first temperature-variable pressure-sensitive adhesive sheet 31 so that the electrode portion 13 of the micro LED 15A is exposed to the outside in order to solve this problem. The structure of moving the micro LED (15A) to (32) once more was applied. That is, the electrode part 13 of the micro LED 15A may be in close contact with and bonded to the bonding layer 41 of the target device 40 through the second temperature-variable adhesive sheet 32.

In addition, the micro LED selective transfer method according to the present invention is completely separated after the transfer of the first selected micro LED 15A from the substrate 11 to the target device 40 is completed, that is, after the transfer step S40 is completed. After the step (S30), the micro LEDs 15 selected secondary and tertiary among the micro LEDs 15 remaining on the substrate 11 are sequentially separated from the substrate 11 and sequentially applied to the target device 40. It further includes a repeating step (S50) of repeating the preliminary separation step (S20) of FIG. 2 to the complete separation step (S30) and the transfer step (S40) so that the transfer can be performed.

As described above, the micro LED selective transfer method according to the first embodiment of the present invention uses a femtosecond laser to selectively transfer the micro LED from the substrate to the target device, compared to the conventional transfer method, which is a large area processing, temperature-variable adhesive sheet. It can be very easy to control the adhesion of the micro LED and transfer of the micro LED, and since it does not use a laser, there is an advantage of less burning of the adhesive sheet and less damage to the micro LED.

Meanwhile, FIGS. 14 to 26 illustrate a method of selectively transferring a micro LED according to a second embodiment of the present invention.

14 to 26, the selective transfer method of the micro LED according to the second embodiment of the present invention includes a micro LED manufacturing step (S10), a preliminary separation step (S20), a complete separation step (S30), It comprises a transfer step (S40).

The method for selectively transferring micro LEDs according to the second embodiment of the present invention includes a method for selectively transferring micro LEDs according to the first embodiment of the present invention described with reference to FIGS. 1 to 13 and an electrode part to a semiconductor structure or micro LED. The order of the electrode part forming step for forming the protective layer and the protective layer forming step is different, but the other methods are the same as the selective transfer method of the micro LED according to the first embodiment of the present invention.

The electrode part forming step and the protective film forming step of the method for selectively transferring micro LEDs according to the second embodiment of the present invention are described with reference to FIGS. 1 to 13 in the method for selectively transferring micro LEDs according to the first embodiment of the present invention. It is not performed between the etching step (S24) and the second removing step (S25) of the preliminary separation step (S20), but is performed after the etching step of the micro LED manufacturing step (S10) before the preliminary separation step (S20).

In the electrode part formation step, a p-type electrode formed on the p-type semiconductor after the etching step of the micro LED manufacturing step (S10), an n-type electrode formed on the n-type semiconductor exposed to the outside through the etching step, a reflective electrode, and An electrode part 13 including a transparent electrode is formed on the micro LED 15.

In the protective film forming step, a protective film is formed by wrapping the upper portion of the micro LED 15 excluding the electrode part 13 with a protective film so as to protect the upper part of the micro LED 15 on which the electrode part 13 is formed.

In the method of selective transfer of micro LEDs according to the first embodiment of the present invention described above, as shown in FIGS. 4 and 5, the electrode part forming step and the protective film forming step are formed in the preliminary separation step, but the second embodiment of the present invention Since the electrode part formation step and the protective film formation step of the selection transfer method of the micro LED according to the example are performed in advance in the micro LED manufacturing step (S10) as shown in FIG. 14, the preliminary separation step of FIGS. It is different from the selective transfer method of the micro LED according to the first embodiment of the present invention in that the step of forming the electrode part and the protective film after the first removing step of exposing the secondary selected micro LED to the outside is omitted.

Micro LED manufacturing step (S10) includes a semiconductor structure forming step of forming a semiconductor structure (hereinafter, micro LED 15) including a p-type semiconductor layer, an n-type semiconductor layer and an active layer on the substrate 11, and a micro LED (15) A micro LED 15 is manufactured including an etching step of forming a mesa structure by etching a part of the micro LED 15 to expose a part of the p-type semiconductor layer or the n-type semiconductor layer to the outside. .

In the preliminary separation step (S20), only the micro LED 15A selected primarily among the micro LEDs 15 formed on the substrate 11 as shown in FIGS. 15 to 20 is a photoresist 21 and a photomask 22 , As a step of separating a certain portion from the substrate 11 using an exposure apparatus and an etching solution, a coating step (S21), an exposure step (S22), a first removal step (S23), an etching step (S24), and , And a second removing step (S25).

In the coating step (S21), as shown in FIG. 15, a photoresist 21 is applied on the upper portion of the substrate 11 so as to surround all the micro LEDs 15 on the substrate 11.

The exposure step (S22) is a specific area 21A of the photoresist 21 surrounding the micro LED 15A that is primarily selected from among the micro LEDs 15 using a photomask and an exposure apparatus, as shown in FIG. Only the remaining areas except for are selectively exposed.

The photoresist 21 is of a negative type that is inherently soluble in a special chemical or solution but becomes insoluble when exposed to light, and on the contrary, a positive type that is inherently insoluble in a special chemical or solution but changes to soluble when exposed to light. However, in the present embodiment, the former is applied, but the latter can be applied.

The first removing step (S23) removes a specific region 21A of the photoresist 21 surrounding the micro LED 15A that is primarily selected from among the micro LEDs 15 as shown in FIG. 17, that is, a photomask ( The specific area 21A of the photoresist 21 that has not been lighted by 22) is removed using a separate special chemical or solution to expose the firstly selected micro LED 15A to the outside. As the drug or solution applied in the first removal step (S23), Tetramethylammonium hydroxide, ethyl lactate and diacetone alcohol may be used.

The etching step (S24) is a step of separating a predetermined portion from the substrate 11 of the micro LEDs 15A, which are primarily selected among the micro LEDs 15, using an etching solution as shown in FIG. 18. After the whole is immersed in the etching solution, a portion of the first selected micro LED 15A is separated from the substrate 11 by etching the bonding portion between the firstly selected micro LED 15A and the substrate 11 by a CLO method.

Referring to FIG. 18, the firstly selected micro LED (15A) is removed so that only about 15% of the bonding force with the substrate 11 remains or about 85% of the bonding force is removed through the etching step (S24). Can be. At this time, the remaining micro LEDs 15 except for the firstly selected micro LED 15A are protected by the photoresist 21 so that the bonding force to the substrate 11 is not removed or weakened.

As the etching solution used in the etching step (S24), potassium hydroxide (KOH) or hydrofluoric acid (HF) can be applied depending on the type of substrate, and potassium hydroxide (KOH) is used when applying a Si substrate, and a GaAs substrate When applying, hydrofluoric acid (HF) is used.

The second removal step (S25) is the rest of the photoresist 21 surrounding the remaining micro LEDs 15 other than the micro LEDs 15A selected primarily among the micro LEDs 15 as shown in FIGS. 18 and 19. As a step of completely removing the region, the remaining region of the photoresist 21 may be removed through acetone, oxygen plasma treatment, and 1-methyl-2-pyrrolidone (NMP).

After the second removal step (S25), as shown in FIG. 20, only a level of about 15% of the bonding force between the micro LED 15 and the substrate 11 in the previous etching step (S24) remains about 15% compared to the original bonding force. In this state, the etching step (S24) of removing the bonding force so that only about 5% of the bonding force between the micro LED 15 and the substrate 11 remains, may be repeated once more.

In the complete separation step (S30), after attaching and fixing the micro LEDs 15 on the substrate 11 to the first temperature-variable pressure-sensitive adhesive sheet 31 where adhesive strength occurs, weakens or disappears according to temperature conditions, Only the LED 15A is completely separated from the substrate 11.

The complete separation step (S30) is a first temperature-variable adhesive by turning the substrate 11 over so that the micro LED 15 on the substrate 11 is in close contact with the first temperature-variable adhesive sheet 31 at room temperature as shown in FIG. The first temperature-variable pressure-sensitive adhesive sheet 31 is in close contact with the sheet 31 and generates adhesive force on the first temperature-variable pressure-sensitive adhesive sheet 31 so that the micro LED 15 is adhered and fixed to the first temperature-variable pressure-sensitive adhesive sheet 31 ), and the substrate 11 is separated from the first temperature-variable adhesive sheet 31 as shown in FIG. 22.

The first temperature-variable adhesive sheet 31 applied in the complete separation step (S30) applies a cool-off type in which adhesive force occurs above the set reference temperature, and the adhesive force disappears below the set reference temperature, and the first temperature is variable. The first temperature-variable pressure-sensitive adhesive sheet 31 is heated to a level of room temperature so that the micro LED 15A in close contact with the pressure-sensitive adhesive sheet 31 is adhered and fixed to the first temperature-variable pressure-sensitive adhesive sheet 31.

The micro LED 15A, which is primarily selected through the complete separation step S30, is completely separated from the substrate 11 and is moved to the first temperature-variable adhesive sheet 31 at the same time.

The transfer step (S40) is a step of transferring the micro LED 15A moved from the substrate 11 to the first temperature-variable adhesive sheet 31 to the target device 40 as shown in FIGS. 23 to 26, It includes a first transfer step (S41) and a second transfer step (S42).

The first transfer step (S41) is a first temperature so that the micro LED (15A) on the first temperature-variable adhesive sheet 31 is in close contact with the second temperature-variable adhesive sheet 32 of another type as shown in FIG. The first for the micro LED 15A so that the variable adhesive sheet 31 is turned over and in close contact with the second temperature-variable adhesive sheet 32, and the micro LED 15A can be moved to the second temperature-variable adhesive sheet 32. The first temperature-variable adhesive sheet 31 and the second temperature-variable adhesive to extinguish the adhesive force of the temperature-variable adhesive sheet 31 and to generate the adhesive force of the second temperature-variable adhesive sheet 32 to the micro LED 15A. The temperature of the sheet 32 is adjusted respectively, and the first temperature-variable adhesive sheet 31 is separated from the second temperature-variable adhesive sheet 32 as shown in FIG. 24.

The second temperature-variable pressure-sensitive adhesive sheet 32 applied in the first transfer step (S41) weakens or disappears above a set reference temperature (for example, at room temperature), and a warm-off in which adhesion occurs below the set reference temperature. Type is applied, and in the temperature adjustment step of the first transfer step (S41), the micro LED 15A in close contact with the second temperature-variable adhesive sheet 32 is attached and fixed to the second temperature-variable adhesive sheet 32. The 1 temperature-variable adhesive sheet and the second temperature-variable adhesive sheet 32 are cooled below a set reference temperature.

As shown in FIG. 24, the micro LED 15A of the first temperature-variable adhesive sheet 31 is completely moved to the second temperature-variable adhesive sheet 32 through the first transfer step (S41).

And, the second transfer step (S42) is a step of moving the micro LED (15A) moved to the second temperature-variable adhesive sheet 32 through the first transfer step (S41) to the target device 40, FIG. 25 As shown in the second temperature-variable pressure-sensitive adhesive sheet 32 so that the electrode portion 13 of the micro LED 15A transferred to the second temperature-variable pressure-sensitive adhesive sheet 32 faces the bonding layer 41 of the target device 40 ( 32) is in close contact with the target device 40, and the temperature of the second temperature-variable pressure-sensitive adhesive sheet 32 is adjusted to extinguish the adhesive force of the second temperature-variable pressure-sensitive adhesive sheet 32 to the micro LED 15A. As shown in FIG. 26, by separating the second temperature-variable pressure-sensitive adhesive sheet 32 from the target device 40, the transfer process of the micro LED 15A that is primarily selected to the target device 40 is completed.

In the second transfer step (S42), the second temperature-variable adhesive sheet 32 so that the micro LED 15 in close contact with the bonding layer 41 of the target device 40 remains in the bonding layer 41 of the target device 40. ) Is heated above the set reference temperature or at room temperature.

The transfer step (S40) of the micro LED selection transfer method according to the present invention is divided into a first transfer step (S41) and a second transfer step (S42) through a complete separation step (S30). In the state that the electrode part 13 of the micro LED 15A moved to 31 is adhered and fixed to the first temperature-variable adhesive sheet 31, the electrode part 13 of the micro LED 15A is applied to the target device 40. ) Because it is impossible to bond to the bonding layer 41 of the second temperature-variable pressure-sensitive adhesive sheet from the first temperature-variable pressure-sensitive adhesive sheet 31 so that the electrode portion 13 of the micro LED 15A is exposed to the outside in order to solve this problem. The structure of moving the micro LED (15A) to (32) once more was applied. That is, the electrode part 13 of the micro LED 15A may be in close contact with and bonded to the bonding layer 41 of the target device 40 through the second temperature-variable adhesive sheet 32.

In addition, the micro LED selective transfer method according to the present invention is completely separated after the transfer of the first selected micro LED 15A from the substrate 11 to the target device 40 is completed, that is, after the transfer step S40 is completed. After the step (S30), the micro LEDs 15 selected secondary and tertiary among the micro LEDs 15 remaining on the substrate 11 are sequentially separated from the substrate 11 and sequentially applied to the target device 40. It further includes a preliminary separation step (S20), a complete separation step (S30), and a repeating step (S50) of repeating the transfer step (S40) so as to be transferred to each other.

On the other hand, Figures 27 to 38 illustrate a method of selectively transferring a micro LED according to a third embodiment of the present invention. Referring to Figures to 38, the selective transfer method of the micro LED according to the third embodiment of the present invention is a micro LED manufacturing step (S100), a preliminary separation step (S200), a complete separation step (S300), and transfer It is configured including a step (S400).

Micro LED manufacturing step (S100) is a micro LED forming step of forming the micro LED 15 on the substrate 11, and a part of the micro LED 15 so that a part of the semiconductor layer inside the micro LED 15 is exposed to the outside. The etching step of etching, the electrode part forming step of forming the electrode part 13 on the top of the micro LED 15, and the micro LED 15 excluding the electrode part 13 to protect the top of the micro LED 15 It includes the step of forming a protective film by wrapping the upper portion of the protective film with a protective film.

The electrode part forming step and the protective film forming step may be performed in the micro LED manufacturing step (S100), but in the etching solution as in the preliminary separation step (S20) of the selective transfer method of the micro LED according to the first embodiment of the present invention. The micro LED 15 on the substrate 11 can be partially separated from the substrate 11 by using an etching solution so as to prevent damage to the electrode part 13 by the preliminary separation step (S200). Of course.

In the preliminary separation step (S200), the substrate 11 is immersed in an etching solution to partially separate all the micro LEDs 15 on the substrate 11 from the substrate 11 using an etching solution. In the preliminary separation step (S200), the bonding strength between the micro LED 15 and the substrate 11 as shown in FIG. 28 and the etching step (S24) of the selective transfer method of the micro LED according to the first embodiment of the present invention Only about 15% to 5% of the original bonding strength between each other is maintained or about 85% to 95% can be removed.

The complete separation step (S300) is a first among micro LEDs 15 on the substrate 11 using a temperature-variable pressure-sensitive adhesive sheet that generates, weakens or disappears according to temperature conditions, and a mask made of PET and formed in a specific pattern. After bonding and fixing only the selected micro LEDs 15A on the temperature-variable adhesive sheet, only the firstly selected micro LEDs 15A are completely separated from the substrate 11.

The complete separation step (S300) includes a thin film forming step (S301), a mask forming step (S302), a mask transferring step (S303), and a selective separation step (S304).

In the thin film forming step (S301), as shown in FIG. 29, a first temperature-variable adhesive sheet 31 is prepared, and PET is applied very thinly on the first temperature-variable adhesive sheet 31 to form a PET thin film layer 35. To form.

In the mask forming step (S302), as shown in FIG. 30, the micro LED 15A to be primarily transferred to the target device 40, that is, a specific location corresponding to the position and arrangement of the micro LED 15A selected primarily The PET thin film layer 35 is laser processed as a pattern to form a PET mask 36 of a specific pattern.

In the mask transfer step (S303), as shown in FIG. 31, a second temperature-variable adhesive sheet 32 is prepared, and the first temperature-variable adhesive sheet 31 is turned over to form a PET mask on the first temperature-variable adhesive sheet 31. (36) is in close contact with the second temperature-variable adhesive sheet 32, and the adhesive force of the first temperature-variable adhesive sheet 31 is extinguished or weakened, and the adhesive force of the second temperature-variable adhesive sheet 32 is generated. The temperature of the variable pressure-sensitive adhesive sheet 31 and the second temperature-variable pressure-sensitive adhesive sheet 32 is respectively controlled, and the PET mask 36 is adhered and fixed to the second temperature-variable pressure-sensitive adhesive sheet 32, as shown in FIG. As described above, the first temperature-variable adhesive sheet 31 is separated from the second temperature-variable adhesive sheet 32 and the PET mask 36 is completely transferred to the second temperature-variable adhesive sheet 32.

The first temperature-variable pressure-sensitive adhesive sheet 31 of the mask transfer step (S303) applies a warm-off type in which the adhesive strength is weakened or disappears above the set reference temperature (for example, at room temperature), and the adhesive force occurs below the set reference temperature. In addition, the second temperature-variable pressure-sensitive adhesive sheet 32 was applied with a cool-off type in which adhesive force was generated above the set reference temperature and the adhesive force disappeared below the set reference temperature. Unlike this, it goes without saying that the first temperature-variable adhesive sheet 31 may be applied as a warm-off type and the second temperature-variable adhesive sheet 32 may be applied as a cool-off type.

In the selective separation step (S304), the micro LED 15 partially separated from the substrate 11 through the preliminary separation step (S200) as shown in FIG. 33 is removed from the second area except the area to which the PET mask 36 is adhered. The second temperature-variable pressure-sensitive adhesive sheet 32 and the substrate 11 are in close contact with each other to adhere and fix the temperature-variable pressure-sensitive adhesive sheet 32, and a second temperature to generate adhesive force on the second temperature-variable pressure-sensitive adhesive sheet 32. Adjust the temperature of the variable pressure-sensitive adhesive sheet 32, and after the micro LED (15A) is adhered and fixed to the second temperature-variable pressure-sensitive adhesive sheet 32, from the second temperature-variable pressure-sensitive adhesive sheet 32 as shown in FIG. Separating the substrate 11 completely separates the micro LED 15 from the substrate 11.

Through the selective separation step (S304), the micro LED 15A, which is primarily selected by the PET mask 36, is completely separated from the substrate 11 and completely moved to the second temperature-variable adhesive sheet 32.

Transfer step (S400) is a step of transferring the micro LED 15 moved from the substrate 11 to the second temperature-variable adhesive sheet 32 to the target device 40, the first transfer step (S410) and the second It includes a transfer step (S420).

In the first transfer step (S410), the micro LED 15 and the PET mask 36 adhered and fixed to the second temperature-variable pressure-sensitive adhesive sheet 32 as shown in 35 are converted into a third temperature-variable pressure-sensitive adhesive sheet 33. As a step of transferring, the second temperature-variable adhesive sheet 32 is in close contact with the third temperature-variable adhesive sheet 33.

In addition, the temperature of the second temperature-variable pressure-sensitive adhesive sheet 32 is adjusted so that the adhesive force of the second temperature-variable pressure-sensitive adhesive sheet 32 is weakened or disappeared, and the third temperature is modified so that the adhesive force of the third temperature-variable pressure-sensitive adhesive sheet 33 occurs. The temperature of the adhesive sheet 33 is adjusted.

After the micro LED 15 and the PET mask 36 are adhered and fixed to the third temperature-variable adhesive sheet 33, the second temperature-variable adhesive sheet 32 is separated from the third temperature-variable adhesive sheet 33. .

As shown in FIG. 36, the micro LED 15A and the PET mask 36 on the second temperature-variable adhesive sheet 32 are transferred to the third temperature-variable adhesive sheet 33 through the first transfer step (S410). .

The second transfer step (S420) is a step of transferring the micro LEDs 15 adhered and fixed to the third temperature-variable adhesive sheet 33 to the target device 40, as shown in FIG. 37. The third temperature-variable adhesive sheet 33 is applied to the target device 40 so that the electrode portion 13 of the micro LED 15A on the adhesive sheet 33 is bonded to the bonding layer 41 provided on the target device 40. And the temperature of the third temperature-variable pressure-sensitive adhesive sheet 33 is adjusted so that the adhesive force of the third temperature-variable pressure-sensitive adhesive sheet 33 is weakened or disappears. And, after the electrode part 13 of the micro LED 15A is bonded to the bonding layer 41 of the target device 40, as shown in FIG. 38, the third temperature-variable pressure-sensitive adhesive sheet 33 is applied to the target device ( 40).

Through the second transfer step (S420), the micro LED 15 on the third temperature-variable adhesive sheet 33 is transferred to the target device 40.

The third temperature-variable pressure-sensitive adhesive sheet 33 applied in the second transfer step (S420) As in the first temperature-variable pressure-sensitive adhesive sheet 31 described above, the adhesive strength is weakened or disappears above the set reference temperature (for example, the room temperature level), Below the set reference temperature, a warm-off type that generates adhesion is applied.

The transfer step (S400) of the micro LED selection transfer method according to the present embodiment is divided into a first transfer step (S410) and a second transfer step (S420), and the second temperature is changed through the complete separation step (S300). When the electrode part 13 of the micro LED 15A moved to the adhesive sheet 32 is adhered and fixed to the second temperature-variable adhesive sheet 32, the electrode part 13 of the micro LED 15A is targeted to the target device. Since it is impossible to bond to the bonding layer 41 of 40, in order to solve this problem, the electrode part 13 of the micro LED 15A is exposed to the outside so that the third temperature is variable from the second temperature-variable adhesive sheet 32. The structure of moving the micro LED (15A) once more with the adhesive sheet 33 was applied. That is, the electrode part 13 of the micro LED 15A may be in close contact with and bonded to the bonding layer 41 of the target device 40 through the third temperature-variable adhesive sheet 33.

In addition, in the transfer step (S400), when moving the micro LED 15A from the second temperature-variable adhesive sheet 32 to the third temperature-variable adhesive sheet 33, the second temperature-variable adhesive together with the PET mask 36 Although a structure for moving from the sheet 32 to the third temperature-variable pressure-sensitive adhesive sheet 33 is applied, it is of course possible to move only the micro LED 15 excluding the PET mask 36 differently.

In addition, the micro LED selection transfer method according to the present embodiment is complete after the transfer of the micro LED 15A that is first selected from the substrate 11 to the target device 40 is completed, that is, after the transfer step S400 is completed. After the separation step (S300), the micro LEDs 15 selected secondary and tertiary among the micro LEDs 15 remaining on the substrate 11 are sequentially separated from the substrate 11 and transferred to the target device 40. It further includes a complete separation step (S300) and a repeating step (S500) of repeating the transfer step (S400) to be transferred sequentially.

In this case, the third temperature-variable adhesive sheet 33 in a state in which the micro LED 15A used in the second transfer step S420 is completely separated, and the PET mask 36 is a third temperature-variable adhesive sheet 33 ), and the first temperature-variable pressure-sensitive adhesive sheet 31 and the third temperature-variable pressure-sensitive adhesive sheet 32 have the same characteristics in terms of temperature conditions, so in the repeating step (S500), the complete separation step ( The thin film forming step (S301) and the mask forming step (S302) shown in FIGS. 29 to 30 of S300) may be omitted, and the third temperature-variable adhesive sheet 33 is a mask transfer step as shown in FIG. It can be reused in place of the first temperature-variable adhesive sheet 31 in (S303).

The selection and transfer method of the micro LED according to the present invention described above has been described with reference to the accompanying drawings, but this is only illustrative, and various modifications and other equivalent embodiments are provided from those of ordinary skill in the art. You will understand that it is possible.

Therefore, the scope of the true technical protection of the present invention should be determined only by the technical spirit of the appended claims.

11: substrate
13: electrode part
15: Micro LED
15A: Primary selected micro LED
21: photoresist
22: photo mask
31: the first temperature-variable adhesive sheet
32: second temperature variable adhesive sheet
33: 3rd temperature variable adhesive sheet
40: target device
41: bonding layer
S10: Micro LED manufacturing step
S20: Preliminary separation step
S21: Application step
S22: Exposure step
S23: First removal step
S24: etching step
S25: second removal step
S30: Complete separation step
S40: Warrior stage
S41: First Warrior Stage
S42: 2nd Warrior Stage

Claims (6)

delete delete delete delete Forming a semiconductor structure on a substrate, etching a part of the semiconductor structure so that a part of the semiconductor layer inside the semiconductor structure is exposed to the outside, an electrode part forming step of forming an electrode part on the semiconductor structure, A micro LED manufacturing step of manufacturing a micro LED, including wrapping an upper portion of the semiconductor structure excluding the electrode portion with a protective film to protect the upper portion of the semiconductor structure;
A preliminary separation step of separating all the micro LEDs on the substrate from the substrate by using an etching solution;
A second temperature-variable pressure-sensitive adhesive sheet that generates, weakens or disappears according to temperature conditions, and is formed in a specific pattern on the second temperature-variable pressure-sensitive adhesive sheet, and is primarily selected from micro LEDs on the substrate using a mask made of PET A complete separation step of completely separating only the firstly selected micro LED from the substrate after bonding and fixing only the micro LED to the second temperature-variable adhesive sheet;
A transfer step of transferring the micro LED moved from the substrate to the second temperature-variable adhesive sheet to a target device; including,
After the transfer step, after the complete separation step, the second and third micro LEDs selected from among the micro LEDs remaining on the substrate are sequentially separated from the substrate and transferred to the target device. The separation step and the repeating step of repeating the transfer step further comprises,
The transfer step
The second temperature-variable pressure-sensitive adhesive sheet is in close contact with a third temperature-variable pressure-sensitive adhesive sheet to move the micro LED on the second temperature-variable pressure-sensitive adhesive sheet to a third temperature-variable pressure-sensitive adhesive sheet, and the second temperature-variable pressure-sensitive adhesive sheet and the third A first transfer step of controlling the temperature of the temperature-variable adhesive sheet and separating the second temperature-variable adhesive sheet from the third temperature-variable adhesive sheet,
The third temperature-variable pressure-sensitive adhesive sheet is in close contact with the target device so that the electrode portion of the micro LED transferred to the third temperature-variable pressure-sensitive adhesive sheet is bonded to the bonding layer of the target device, and the temperature of the third temperature-variable pressure-sensitive adhesive sheet is adjusted. And a second transfer step of separating the temperature-variable adhesive sheet from the target device,
The second temperature-variable adhesive sheet applies a warm-off type in which adhesive strength is weakened or disappears above a set reference temperature and adhesive strength occurs below a set reference temperature, and the third temperature-variable adhesive sheet is adhesive strength above a set reference temperature. A method of selective transfer of micro LEDs, characterized in that a cool-off type in which the adhesive force disappears below the set reference temperature and when this occurs.
The method of claim 5,
The complete separation step
A thin film forming step of forming a PET thin film layer on the first temperature-variable pressure-sensitive adhesive sheet,
A mask forming step of forming a PET mask by laser processing the PET thin film layer in a specific pattern corresponding to the position of the micro LED that is primarily selected,
A mask transfer step of transferring the mask to a second temperature-variable adhesive sheet,
After the second temperature-variable adhesive sheet and the substrate are in close contact with each other to adhere and fix the micro-LED partially separated from the substrate through the preliminary separation step on the second temperature-variable adhesive sheet excluding the mask, the Selective transfer method of micro LED, characterized in that it comprises a separation step of completely separating the micro LED from the substrate.

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