Method for transferring micro device

Abstract

The present invention relates to a method for transferring a micro device that is capable of transferring, cleaning, and repairing a micro device at the same position by using an ultra-short pulse laser. The method comprises: a picking step of transferring a micro device disposed on a source substrate to an adhesive portion of a carrier; a placing step of placing the carrier on a target substrate and then irradiating the carrier with an ultra-short pulse laser so as to transfer the micro device to the target substrate; a scanning step of determining a state of the micro device transferred to the target substrate; and a cleaning step of removing foreign substances by irradiating the ultra-short pulse laser when it is determined that foreign substances have remained on the surface of the micro device in the scanning step. Through this method, the effect of improving work efficiency and speed can be obtained by transferring the micro device at the same position by using the ultra-short pulse laser, and then immediately scanning the transferred micro device and cleaning the micro device having foreign substances remaining.

Description

Micro-element transfer method

[0001] The present invention relates to a micro-element transfer method, and more particularly, to a micro-element transfer method capable of transferring, cleaning, and repairing micro-elements at the same location using an ultra-short pulse laser.

[0002] Recently, there has been a growing demand for technologies capable of mass-transferring LED chips from a source substrate to a target substrate in applications such as microLEDs (light-emitting diodes) and thin wafer packaging. Various transfer techniques have been proposed, but laser-based transfer is attracting attention due to its high process speed, selectivity, and high area scalability.

[0003] Micro LEDs are generally manufactured with a chip size of 10 to 100㎛ and can be applied to all optical applications that require low power consumption, miniaturization, and lightweight.

[0004] By manufacturing LED chips in this way to a size of tens of microns, the disadvantage of inorganic materials being prone to breaking when bent can be overcome, and they can be widely used in flexible displays, smart fibers combining fibers and LEDs, medical devices attached to and implanted in the human body, bio-contact lenses, HMDs (Head Mounted Displays), and wireless communications.

[0005] However, in order for micro LED light sources to be applied in these various application fields, the development of a process technology for transferring individual or arrayed micro LED chips onto a flexible substrate based on flexible materials / elements is a top priority.

[0006] The high-speed laser transfer process is a technology that can transfer thin-film chips of 10㎛ or less at high speed with high precision without damage, and high-speed transfer is possible based on a high-speed pulse laser and high-speed beam control.

[0007] Meanwhile, known laser thermal transfer mechanisms include ablation transfer, thermal transfer, and thermal mechanical transfer.

[0008] In the ablation transfer mechanism, a sacrificial layer is vaporized by laser ablation and the chip can be transferred using the vapor pressure generated thereby. However, it is difficult to control the strength and shape of the vapor pressure, making it difficult to secure transfer alignment and also posing a risk of damage to the chip.

[0009] In the thermal transfer mechanism, the adhesive strength of the adhesive layer is reduced by the laser heat, and the chip can be transferred by this reduction in adhesive strength and the gravity of the chip, but it has the disadvantage of being sensitive to the adhesive layer and laser conditions, and thus has a high probability of transfer failure.

[0010] In contrast, in the thermomechanical transfer mechanism, the polymer-based absorbing layer of the DRL (Dynamic Release Layer), which consists of two layers: an absorbing layer and an adhesive layer, absorbs laser light, generating blisters that push out the chip. The chip attached to the adhesive layer is then transferred to the substrate due to the reduced bonding area and gravity. This is a high-speed process, and since the laser is not directly transmitted to the chip, it is non-damaging, and it is transmitted to the substrate, enabling precise positioning.

[0011] However, as the size of the chip and the distance between chips become smaller due to the demand for high resolution, there is a problem that precise transfer becomes difficult due to interference with neighboring chips of the transferred chip due to the size of the blisters generated by absorbing the laser light.

[0012] In addition, after transferring the chip to the target substrate, adhesive residue remains on the upper surface of the chip, which is difficult to remove, and in case the transferred chip is damaged, it is difficult to selectively remove (repair) the chip.

[0013] The present invention was created to solve the above problems, and its purpose is to provide a micro-element transfer method capable of transferring, cleaning, and repairing micro-elements at the same location.

[0014] In order to achieve the above object, a micro-element transfer method according to a preferred embodiment of the present invention may include a picking step for transferring a micro-element placed on a source substrate to an adhesive portion of a carrier; a placing step for transferring the micro-element to the target substrate by irradiating the carrier with an ultra-short pulse laser after placing the carrier on a target substrate; a scanning step for determining the state of the micro-element transferred to the target substrate; and a cleaning step for removing the foreign matter by irradiating an ultra-short pulse laser when it is determined in the scanning step that a foreign matter remains on the surface of the micro-element.

[0015] According to the micro-element transfer method of the present invention, after transferring a micro-element at the same location using an ultra-short pulse laser, the transferred micro-element is immediately scanned to clean any micro-elements with remaining foreign matter and repair any damaged micro-elements, thereby obtaining the effect of improving work efficiency and speed.

[0016] FIG. 1 is a cross-sectional view schematically illustrating a state in which a micro device is transferred by a micro device transfer method according to an embodiment of the present invention.

[0017] Figure 2 is a cross-sectional diagram schematically illustrating a state in which a laser is nonlinearly absorbed in a blister layer by a femtosecond pulse laser.

[0018] Figure 3 is a graph showing the diameter of blisters formed by nanosecond lasers and femtosecond pulse lasers as a function of energy density.

[0019] Figure 4 is a graph showing the aspect ratio (height / diameter) of blisters formed by nanosecond lasers and femtosecond pulse lasers according to energy density.

[0020] Figure 5 is a diagram showing the shape of a blister formed by a nanosecond laser and a femtosecond pulse laser according to energy density.

[0021] Figure 6 is a flowchart schematically showing a micro device transfer method according to an embodiment of the present invention.

[0022] Fig. 7 is a plan view showing a state in which foreign substances in a micro device are removed by a micro device transfer method according to an embodiment of the present invention.

[0023] Figure 8 is a plan view showing a state in which a broken micro-element is removed by a micro-element transfer method according to an embodiment of the present invention.

[0024] In order to achieve the above object, a micro-element transfer method according to a preferred embodiment of the present invention may include a picking step for transferring a micro-element placed on a source substrate to an adhesive portion of a carrier; a placing step for transferring the micro-element to the target substrate by irradiating the carrier with an ultra-short pulse laser after placing the carrier on a target substrate; a scanning step for determining the state of the micro-element transferred to the target substrate; and a cleaning step for removing the foreign matter by irradiating an ultra-short pulse laser when it is determined in the scanning step that a foreign matter remains on the surface of the micro-element.

[0025] Here, the cleaning step may be performed by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm, a pulse width of 10 fs to 100 ps, ​​a repetition rate of 50 to 1,000 kHz, and an output of 0.5 to 5 W.

[0026] Additionally, the cleaning step may be performed by irradiating an ultrashort pulse laser having a beam diameter of ±40% of the micro-element size.

[0027] Furthermore, the cleaning step may further include a suction step for suctioning and removing fumes generated during the removal of foreign substances.

[0028] In addition, the micro-element transfer method of the present invention may further include a repair step of removing the damaged micro-element by irradiating it with an ultra-short pulse laser if the micro-element is determined to be damaged in the scanning step.

[0029] The above repair step can be performed by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm, a pulse width of 10 fs to 100 ps, ​​a repetition rate of 50 to 1,000 kHz, and an output of 0.5 to 5 W.

[0030] And, the above repair step can be performed by irradiating an ultrashort pulse laser having a beam diameter of 10 to 50 μm.

[0031] Additionally, the above repair step may be performed by removing the damaged micro-element by irradiating it with an ultrashort pulse laser in a zigzag pattern.

[0032] Furthermore, the repair step may further include a suction step for suctioning and removing fumes generated when removing a damaged micro-element.

[0033] The above placing step can be performed by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm.

[0034] And, the above placing step can be performed to irradiate an ultrashort pulse laser having a pulse width of 10 fs to 100 ps.

[0035] Additionally, the above placing step may be performed by irradiating a femtosecond pulse laser having a wavelength of 900 to 3,000 nm.

[0036] More specifically, the placing step may be performed by irradiating a femtosecond pulse laser having a pulse width of 10 to 800 fs.

[0037] The above placing step may be performed such that an ultrashort pulse laser passes through a portion of the blister layer formed on the carrier and is nonlinearly absorbed in a specific area inside the blister layer to form a high aspect ratio blister, thereby deforming the adhesive layer and causing the micro device to detach.

[0038] Here, the diameter of the blister formed in the blister layer may be formed smaller than the diameter of the ultrashort pulse laser beam irradiated onto the blister layer.

[0039] And, the placing step may be performed to form a blister having a diameter of 1 to 40 μm by irradiating the blister layer with a femtosecond pulse laser having a diameter of 1 to 40 μm at an energy density of 0.1 to 2.0 J / cm2.

[0040] In addition, the placing step may be performed to form a blister having an aspect ratio (height / diameter) of 0.2 to 2 by irradiating the blister layer with a femtosecond pulse laser.

[0041] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0042] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. This is not intended to limit the invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0043] The terminology used in this application is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions may include plural expressions, unless the context clearly dictates otherwise.

[0044] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries, such as those defined in the present application, may be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and, unless explicitly defined herein, may not be interpreted in an idealized or overly formal sense.

[0045] Hereinafter, specific embodiments of the present invention will be described with reference to the attached drawings.

[0046] FIG. 1 is a cross-sectional view schematically illustrating a state in which a micro device is transferred by a micro device transfer method according to an embodiment of the present invention, FIG. 2 is a cross-sectional view schematically illustrating a state in which a laser is nonlinearly absorbed in a blister layer by a femtosecond pulse laser, FIG. 3 is a graph showing the diameter of a blister formed by a nanosecond laser and a femtosecond pulse laser according to energy density, FIG. 4 is a graph showing the aspect ratio (height / diameter) of a blister formed by a nanosecond laser and a femtosecond pulse laser according to energy density, and FIG. 5 is a drawing showing the shape of a blister formed by a nanosecond laser and a femtosecond pulse laser according to energy density.

[0047] Referring to FIGS. 1 to 5, a transfer device used in a micro-element transfer method according to one embodiment of the present invention may include a laser irradiation unit (200) that irradiates an ultra-short pulse laser (Lfs), and a carrier (100) that detaches the micro-element (C) when the micro-element (C) is adhered and irradiated with the ultra-short pulse laser (Lfs).

[0048] Here, the carrier (100) may include a base layer (110) through which laser is transmitted, an adhesive layer (130) formed on the base layer (110) and to which a micro element (C) is adhered, and a blister layer (120) provided between the base layer (110) and the adhesive layer (130) and which expands when irradiated with an ultrashort pulse laser (Lfs) to deform the adhesive layer (130) and cause the micro element (C) to detach.

[0049] In the present invention, by irradiating an ultrashort pulse laser (Lfs), a blister having a high aspect ratio is formed in the blister layer (120), so that even a micro-element (C) of a smaller size or a micro-element (C) arranged in a micro gap can be transferred more precisely.

[0050] To this end, the laser irradiation unit (200) may be configured to irradiate an ultrashort pulse laser having a wavelength of 500 to 3,000 nm and a pulse width of 10 fs to 100 ps. Preferably, the laser irradiation unit (200) may be configured to irradiate a femtosecond pulse laser having a wavelength of 900 to 3,000 nm and a pulse width of 10 to 800 fs.

[0051] When the femtosecond pulse laser (Lfs) is irradiated onto the carrier (100), it is not absorbed from the surface of the blister layer (120), but as illustrated in FIG. 2, it passes through a portion of the blister layer (120) and is absorbed nonlinearly in a specific region inside the blister layer (120). In addition, the femtosecond pulse laser (Lfs) can locally transfer heat without heat diffusion to the surroundings because the energy transfer time (about 10 -13 to 10 -15 seconds) in the blister layer (120) is shorter than the heat diffusion time (about 10 -12 seconds).

[0052] Through these characteristics, blisters having a high aspect ratio can be formed. Therefore, even when the size of the micro-element is manufactured to be approximately 40 μm or smaller, or when the spacing between the elements is small, the influence of blister formation on the adjacent micro-elements of the transferred micro-element can be prevented, thereby allowing the micro-element (C) to be transferred more precisely.

[0053] Figure 3 shows the results of measuring the diameter (D) of blisters formed by irradiating a nanosecond laser (ns pulse) and a femtosecond pulse laser (fs pulse). Here, the energy density of the irradiated laser was applied in the range of 0.4 to 2.0 J / cm2, and the beam diameter (Beam D) of the nanosecond laser (ns pulse) was 26 μm, and the beam diameter (Beam D) of the femtosecond pulse laser (fs pulse) was 40 μm.

[0054] As illustrated in Fig. 3, a nanosecond laser (ns pulse) was irradiated with a beam diameter of 26 μm. When irradiated with an energy density of 0.6 J / cm2, the diameter (D) of the blister was approximately 30 μm. When irradiated with an energy density of 1.1 J / cm2, the diameter (D) of the blister was approximately 35 μm. When irradiated with an energy density of 1.7 J / cm2, the diameter (D) of the blister was approximately 40 μm. In other words, it can be seen that the diameter (D) of the blister formed is larger than the diameter of the irradiated laser beam.

[0055] This is because in the case of nanosecond lasers, the heat is linearly absorbed in the blister layer, and as the heat spreads to the surroundings, a blister is formed with a diameter larger than the diameter of the laser beam. As a result, when the size of the micro-elements is reduced or the spacing between the elements is small, in the case of nanosecond lasers, a problem may arise in which the blister formation affects the micro-elements arranged adjacent to the micro-elements being transferred.

[0056] In comparison, the femtosecond pulse laser (fs pulse) was irradiated with a beam diameter of 40 μm, which is larger than the beam diameter of the nanosecond laser (ns pulse). However, when irradiated with an energy density of 0.4 J / cm2, the diameter of the blister (D) was approximately 15 μm, when irradiated with an energy density of 0.8 J / cm2, the diameter of the blister (D) was approximately 20 μm, when irradiated with an energy density of 1.4 J / cm2, the diameter of the blister (D) was approximately 25 μm, and when irradiated with an energy density of 2.0 J / cm2, the diameter of the blister (D) was approximately 25 to 30 μm. In other words, it can be seen that the diameter (D) of the formed blister is smaller than the diameter of the irradiated laser beam.

[0057] Therefore, it was confirmed that a femtosecond pulse laser (fs pulse) forms a blister having a diameter smaller than the diameter of the laser beam being irradiated, and that the diameter of the blister does not increase significantly even when the energy density is increased. Therefore, when transferring a micro-element, the blister formation does not affect other micro-elements placed adjacent to the transferred micro-element, enabling more precise transfer of the micro-element.

[0058] Fig. 4 shows the measured aspect ratio (H / D) of blisters formed by irradiating a nanosecond laser (ns pulse) and a femtosecond pulse laser (fs pulse). Here, the energy density of the irradiated laser was applied in the range of 0.4 to 2.0 J / cm2, and the beam diameter (Beam D) of the nanosecond laser (ns pulse) was 26 μm, and the beam diameter (Beam D) of the femtosecond pulse laser (fs pulse) was 40 μm. In addition, Fig. 5 is a drawing showing the shape of a blister formed by irradiating a nanosecond laser (ns pulse) and a femtosecond pulse laser (fs pulse).

[0059] As shown in FIGS. 4 and 5, when a nanosecond laser (ns pulse) is irradiated with an energy density of 0.6 J / cm2, the aspect ratio (H / D) of the blisters is formed to be approximately 0.1 to 0.4, when irradiated with an energy density of 1.1 J / cm2, the aspect ratio (H / D) of the blisters is approximately 0.2 to 0.8, and when irradiated with an energy density of 1.7 J / cm2, the aspect ratio (H / D) of the blisters is approximately 0.1 to 0.3. That is, it can be seen that the aspect ratio (H / D) of the formed blisters increases as the energy density increases and then decreases again. That is, it can be seen that as the energy density increases, the diameter (D) of the blister increases significantly, while the height (H) decreases.

[0060] In comparison, it can be confirmed that when a femtosecond pulse laser (fs pulse) is irradiated with an energy density of 0.4 J / cm2, the aspect ratio (H / D) of the blister is formed to be approximately 0.8 to 0.1, when irradiated with an energy density of 0.8 J / cm2, the aspect ratio (H / D) of the blister is formed to be approximately 0.8 to 0.95, when irradiated with an energy density of 1.4 J / cm2, the aspect ratio (H / D) of the blister is formed to be approximately 0.8 to 0.9, and when irradiated with an energy density of 2.0 J / cm2, the aspect ratio (H / D) of the blister is formed to be approximately 0.8 to 0.85. In other words, it can be confirmed that the height of the blister is formed to be similar to the size of the width, and it can be confirmed that the minimum aspect ratio is maintained at 0.8 even when the energy density increases.

[0061] Therefore, it can be confirmed that femtosecond pulse laser (fs pulse) forms blisters with high aspect ratios compared to nanosecond laser (ns pulse). In conclusion, by irradiating a femtosecond pulse laser beam with a diameter of 40 μm at an energy density of 0.4 to 2.0 J / cm2, blisters with a diameter of 15 to 35 μm and a high aspect ratio of 0.7 to 1.1 can be formed.

[0062] In this way, in the present invention, by irradiating a carrier with a femtosecond pulse laser, a blister having a high aspect ratio is formed, so that even micro-elements of smaller size or micro-elements arranged in a micro-gap can be transferred more precisely.

[0063] FIG. 6 is a flowchart schematically showing a micro-element transfer method according to an embodiment of the present invention, FIG. 7 is a plan view showing a state in which foreign substances from a micro-element are removed by a micro-element transfer method according to an embodiment of the present invention, and FIG. 8 is a plan view showing a state in which a damaged micro-element is removed by a micro-element transfer method according to an embodiment of the present invention.

[0064] First, referring to FIG. 6, a micro-element transfer method according to an embodiment of the present invention includes a picking step (S110) for transferring a micro-element placed on a source substrate to an adhesive portion of a carrier, a placing step (S120) for transferring the micro-element to the target substrate by irradiating the carrier with an ultra-short pulse laser after placing the carrier on a target substrate, a scanning step (S130) for determining the state of the micro-element transferred to the target substrate, and a cleaning step (S140) for removing the foreign matter by irradiating the ultra-short pulse laser if it is determined in the scanning step that a foreign matter remains on the surface of the micro-element.

[0065] In particular, the placing step (S120) may be performed to irradiate an ultrashort pulse laser having a wavelength of 500 to 3,000 nm and a pulse width of 10 fs to 100 ps. Preferably, the placing step (S120) may be performed to irradiate a femtosecond pulse laser having a wavelength of 900 to 3,000 nm and a pulse width of 10 to 800 fs.

[0066] In this placing step (S120), the femtosecond pulse laser irradiated passes through a portion of the blister layer formed on the carrier and is nonlinearly absorbed in a specific area inside the blister layer to form a high aspect ratio blister, thereby deforming the adhesive layer to detach the microelement and transfer it to the target substrate.

[0067] For example, in the placing step (S120), a femtosecond pulse laser beam having a diameter of 1 to 40 μm can be irradiated with an energy density of 0.1 to 2.0 J / cm2 to form a blister having a diameter of 1 to 40 μm and a blister having a high aspect ratio of 0.2 to 2. That is, the diameter of the blister formed in the blister layer is formed to be smaller than the diameter of the femtosecond pulse laser beam irradiated to the blister layer.

[0068] In this way, in the present invention, by irradiating a carrier with a femtosecond pulse laser, a blister having a high aspect ratio is formed, so that even micro-elements of smaller size or micro-elements arranged in a micro-gap can be transferred more precisely.

[0069] Additionally, in the placing step (S120), multiple ultra-short pulse lasers can be irradiated to simultaneously transfer multiple micro-elements to the target substrate.

[0070] The above scanning step (S130) is a step of identifying the state of the micro-elements transferred to the target substrate using a vision device at the same location without moving the target substrate after the micro-elements have been transferred to the target substrate by the placing step (S120).

[0071] The above vision device can capture a micro-element transferred to the target substrate and then determine the status of the micro-element through the captured image.

[0072] In addition, the cleaning step (S140) is a step in which, if it is determined in the scanning step (S130) that foreign substances remain on the surface of the micro element, an ultrashort pulse laser is irradiated on the surface of the micro element where foreign substances remain to remove the foreign substances.

[0073] That is, in the process of transferring the micro element to the target substrate in the above-mentioned placing step (S120), the adhesive of the adhesive portion of the carrier may be transferred while remaining on the surface of the micro element.

[0074] Accordingly, the present invention includes a cleaning step (S140) for identifying such residual foreign matter and irradiating the surface of a micro device with an ultrashort pulse laser to simply and cleanly remove the foreign matter, as shown in FIG. 7.

[0075] To this end, the cleaning step (S140) is performed by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm, a pulse width of 10 fs to 100 ps, ​​a repetition rate of 50 to 1,000 kHz, and an output of 0.5 to 5 W. Here, the beam diameter of the ultrashort pulse laser is adjusted to a size within a range of ±40% of the micro-element size (for example, if the element size is 50 μm, the beam diameter is 20 to 70 μm) by adjusting the defocusing position from the focus to adjust the size, and the laser beam is moved at high speed to the micro-element position with a scanner to irradiate 1 to 5 ultrashort pulse laser pulses to each element to remove foreign substances.

[0076] Figure 7 is a photograph of a state in which foreign matter in a micro device has been removed by irradiating it with an ultrashort pulse laser having a wavelength of 1,040 nm, a pulse width of 350 fs, a repetition rate of 400 kHz, a beam diameter of 30 μm, and an output of 1.5 to 3 W.

[0077] In this cleaning step (S140), the target substrate is left in the same position after the placing step (S120) without being moved, and the laser irradiation unit used in the placing step (S120) is used as is, but the laser being irradiated is reset to suit the cleaning conditions and then the laser is irradiated.

[0078] That is, after determining the state of the transferred micro-element in the scanning step (S130), if it is determined that a foreign substance remains on the surface of the micro-element (example of S140), an ultra-short pulse laser is irradiated on the surface of the micro-element where the foreign substance remains to remove the foreign substance (S141).

[0079] Additionally, fumes may be generated during the process of removing the above-mentioned foreign substances. These fumes may affect wiring formed on the target substrate, thereby causing quality degradation.

[0080] Accordingly, the cleaning step (S140) may further include a suction step (S142) for suctioning and removing fumes generated during the removal of foreign substances.

[0081] This suction step (S142) can be performed by suctioning and removing fumes generated when removing foreign substances through a suction device that is arranged around the target substrate and sucks in air.

[0082] Meanwhile, in the cleaning step (S140), foreign substances in multiple micro elements can be removed simultaneously using multiple ultrashort pulse lasers.

[0083] The micro-element transfer method of the present invention may further include a repair step (S150) of removing the damaged micro-element by irradiating an ultra-short pulse laser if the micro-element is determined to be damaged in the scanning step (S130). Here, the repair step (S150) may be performed by irradiating the damaged micro-element with an ultra-short pulse laser in a zigzag pattern to destroy and remove the damaged micro-element.

[0084] Microdevices may be damaged during the manufacturing process or during the transfer process to the target substrate. In this case, the damaged microdevice must be removed.

[0085] Accordingly, the present invention includes a repair step (S150) of simply and cleanly removing a broken micro-element by irradiating the surface of the broken micro-element with an ultrashort pulse laser, as shown in FIG. 8.

[0086] To this end, the repair step (S150) is performed by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm, a pulse width of 10 fs to 100 ps, ​​a repetition rate of 50 to 1,000 kHz, an output of 0.5 to 5 W, and a beam diameter of 10 to 50 μm. Using this ultrashort pulse laser, the damaged micro-elements can be removed by irradiating each micro-element with the ultrashort pulse laser within a range of +50% of the size of the micro-element.

[0087] Figure 8 is a photograph of a micro device with a size of 50 X 50 μm irradiated with an ultrashort pulse laser having a wavelength of 1,040 nm, a pulse width of 350 fs, a repetition rate of 400 kHz, a beam diameter of 30 μm, and an output of 1 to 2 W, and removed. Here, the ultrashort pulse laser was irradiated in the vertical direction of the micro device to a length of 50 μm, then at intervals of 20 μm in the horizontal direction, and then again in the vertical direction to a length of 50 μm.

[0088] In this repair step (S150), the target substrate is left in the same position after the placing step (S120) without being moved, and the laser irradiation unit used in the placing step (S120) is used as is, but the irradiated laser is reset to suit the repair conditions and then the laser is irradiated.

[0089] That is, after determining the state of the transferred micro-element in the scanning step (S130), if it is determined that there is a broken micro-element (example of S150), an ultra-short pulse laser is irradiated in a zigzag shape on the surface of the broken micro-element to remove the broken micro-element (S151).

[0090] Additionally, fumes may be generated during the process of removing the above micro-elements. These fumes may affect wiring formed on the target substrate as foreign substances, thereby causing quality degradation.

[0091] Accordingly, the above repair step (S150) may further include a suction step (S152) for suctioning and removing fumes generated when removing a damaged micro element.

[0092] This suction step (S152) can be performed to remove fumes generated when removing broken micro-elements by suctioning them through a suction device that is arranged around the periphery of the target substrate and sucks in air.

[0093] Meanwhile, if there are multiple broken micro-elements, multiple ultrashort pulse lasers can be applied simultaneously to remove multiple broken micro-elements simultaneously.

[0094] In this way, the micro-element transfer method according to an embodiment of the present invention transfers a micro-element placed on a carrier to a target substrate using an ultrashort pulse laser, scans the transferred micro-element at the same location without moving the target substrate after transfer, and then, if a foreign substance remains on the transferred micro-substrate, irradiates the ultrashort pulse laser to remove the foreign substance, and if a damaged micro-element exists, irradiates the ultrashort pulse laser to remove the damaged micro-element, thereby improving work efficiency and speed.

[0095] Although the present invention has been described in detail through specific examples, this is for the purpose of specifically explaining the present invention, and the present invention is not limited thereto, and it is clear that the present invention can be modified or improved by a person having ordinary knowledge in the relevant field within the technical spirit of the present invention.

[0096] All simple modifications or changes of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

Claims

1. A picking step for transferring micro-elements placed on a source substrate to an adhesive portion of a carrier; A placing step of placing the carrier on a target substrate and then irradiating the carrier with an ultrashort pulse laser to transfer a micro element to the target substrate; A scanning step for identifying the state of the micro-elements transferred to the target substrate; and If it is determined that foreign matter remains on the surface of the micro device in the above scanning step, a cleaning step is performed to remove the foreign matter by irradiating it with an ultrashort pulse laser; A method for transferring micro-elements including:

2. In paragraph 1, The above cleaning step is, A micro-element transfer method characterized by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm, a pulse width of 10 fs to 100 ps, ​​a repetition rate of 50 to 1,000 kHz, and an output of 0.5 to 5 W.

3. In paragraph 1, The above cleaning step is, A micro-element transfer method characterized by irradiating an ultra-short pulse laser having a beam diameter of ±40% of the micro-element size.

4. In paragraph 1, The above cleaning step is, A suction step that removes the fumes generated when removing foreign substances by suction; A micro device transfer method characterized by further including:

5. In paragraph 1, If it is determined that the micro-element is damaged in the above scanning step, a repair step is performed to remove the damaged micro-element by irradiating it with an ultrashort pulse laser; A micro device transfer method characterized by further including:

6. In paragraph 5, The above repair steps are: A micro-element transfer method characterized by irradiating an ultrashort pulse laser having a wavelength of 500 to 3,000 nm, a pulse width of 10 fs to 100 ps, ​​a repetition rate of 50 to 1,000 kHz, and an output of 0.5 to 5 W.

7. In paragraph 5, The above repair steps are: A micro-element transfer method characterized by irradiating an ultra-short pulse laser having a beam diameter of 10 to 50 μm.

8. In paragraph 5, The above repair steps are: A micro-element transfer method characterized by removing a broken micro-element by irradiating it with an ultrashort pulse laser in a zigzag shape.

9. In paragraph 5, The above repair steps are: A suction step for removing fumes generated when removing broken micro-elements; A micro device transfer method characterized by further including:

10. In paragraph 1, The above placing step is, A micro-element transfer method characterized by irradiating an ultra-short pulse laser having a wavelength of 500 to 3,000 nm.

11. In paragraph 1, The above placing step is, A micro-element transfer method characterized by irradiating an ultra-short pulse laser having a pulse width of 10 fs to 100 ps.

12. In paragraph 1, The above placing step is, A micro-element transfer method characterized by irradiating a femtosecond pulse laser having a wavelength of 900 to 3,000 nm.

13. In paragraph 1, The above placing step is, A micro-element transfer method characterized by irradiating a femtosecond pulse laser having a pulse width of 10 to 800 fs.

14. In paragraph 1, The above placing step is, A micro-element transfer method characterized in that an ultra-short pulse laser passes through a portion of a blister layer formed on the carrier and is nonlinearly absorbed in a specific area inside the blister layer to form a high aspect ratio blister, thereby deforming the adhesive layer and detaching the micro-element.

15. In paragraph 14, A micro-element transfer method, characterized in that the diameter of the blister formed in the above blister layer is smaller than the diameter of the ultra-short pulse laser beam irradiated on the above blister layer.

16. In paragraph 14, The above placing step is, A micro-element transfer method characterized in that a blister having a diameter of 1 to 40 μm is formed by irradiating the blister layer with a femtosecond pulse laser having a diameter of 1 to 40 μm at an energy density of 0.1 to 2.0 J / cm2.

17. In paragraph 14, The above placing step is, A micro device transfer method characterized in that a femtosecond pulse laser is irradiated onto the above blister layer to form a blister having an aspect ratio (height / diameter) of 0.2 to 2.

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