A method for massive transfer of micro-LED chips

Abstract

The present invention provides a method for mass transfer of micro-LED chips, comprising: providing a plurality of carrier substrates, a plurality of monochromatic LEDs, a plurality of transfer marks, a mask, and a receiving substrate; arranging the mask, the monochromatic LED carrier substrate, and the receiving substrate from top to bottom; sequentially placing the monochromatic LED carrier substrate between the mask and the receiving substrate for alignment; the laser spot emitted by the laser performs surface scanning on the mask, so that the monochromatic LEDs and the transfer marks are transferred onto the receiving substrate. By designing different transfer marks and alignment methods, the present invention simplifies the mass transfer process and the subsequent chip packaging process, and at the same time achieves a high utilization rate of chip transfer.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor LEDs, and particularly relates to a method for massively transferring micro-LED chips. Background Art

[0002] The massive transfer technology is the most important part in the manufacturing process of Micro-LEDs, mainly a technology for transferring thousands of Micro-LED chips from a carrier substrate to a target substrate.

[0003] Existing massive transfer technologies mostly target products applied to COG, with a simple alignment method, but lack a set of methods applicable to the massive transfer of micro-LEDs. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for massively transferring micro-LED chips to solve the technical problems existing in the prior art.

[0005] The invention provides the following technical solution. A method for massively transferring micro-LED chips, the method comprising the following steps:

[0006] Step 1: Provide a plurality of carrier substrates, a plurality of monochromatic LEDs, and a plurality of transfer marks, and temporarily bond the monochromatic LEDs and the transfer marks to the corresponding carrier substrates through a photosensitive adhesive layer to form a plurality of monochromatic LED carrier substrates;

[0007] Step 2: Provide a mask, on which a plurality of LED mask holes corresponding to the monochromatic LEDs and a mark mask hole corresponding to the transfer mark are provided;

[0008] Step 3: Provide a receiving substrate, and prepare a receiving adhesive layer on the receiving substrate;

[0009] Step 4: Arrange the mask, the monochromatic LED carrier substrates, and the receiving substrate from top to bottom. Among them, the receiving adhesive layer is disposed opposite to the monochromatic LEDs, the mask is fixedly arranged, and the projections of the monochromatic LED carrier substrates and the receiving substrate in the vertical direction coincide;

[0010] Step 5: Align one of the transfer marks on the monochromatic LED carrier substrate with the mark mask hole on the mask;

[0011] Step 6: After the alignment is completed, a laser is provided above the mask, and the laser spot emitted by the laser follows the movement of the galvanometer mirror, so that the laser spot completes a surface scan on the mask, so that the monochromatic LEDs and the transfer marks are transferred to the receiving substrate.

[0012] Compared with the prior art, the beneficial effects of the present application are as follows: By designing transfer marks corresponding to different monochromatic LEDs, as well as the alignment method of the corresponding mask and the monochromatic LED carrier substrate, the massive transfer of micro-LED chips is realized. By designing transfer marks, the subsequent testing and packaging processes of micro-LED chips are simplified and facilitated. At the same time, through the definition of different transfer marks, high utilization rate of chip transfer is achieved, and the transfer of micro-LED edge chips can be realized to overcome the defects existing in the transfer of small rectangular areas.

[0013] Preferably, several of the monochromatic LEDs are arranged in a rectangular array on the photosensitive adhesive layer, a transfer mark area is reserved on the photosensitive adhesive layer, and several of the transfer marks are arranged in a rectangular array in the transfer mark area.

[0014] Preferably, in the first step, the step of temporarily bonding the monochromatic LED and the transfer mark to the corresponding carrier substrate through the photosensitive adhesive layer includes: preparing a photosensitive adhesive layer with a thickness of 3 um - 20 um on the carrier substrate by means of spin coating, spraying, or film laminating, fitting the monochromatic LED, the transfer mark, and the carrier substrate together, putting them into a press and applying a pressure of 100 kg - 750 kg, and keeping the temperature constant at 150 - 230 °C for 1 - 3 h to complete the temporary bonding of the monochromatic LED, the transfer mark, and the carrier substrate.

[0015] Preferably, in the second step, the mask includes a light-transmitting layer and an opaque layer deposited on the light-transmitting layer. The opaque layer is provided with a mask pattern to expose a part of the light-transmitting layer. The mask pattern is composed of several LED mask holes and one mark mask hole. The light-transmitting layer is made of quartz material, and the opaque layer is a chromium layer.

[0016] Preferably, in the third step, the step of preparing a receiving adhesive layer on the receiving substrate includes: preparing a PDMS layer with a thickness of 1 um - 10 um on the receiving substrate by means of spin coating or spraying, and then putting it into an oven and curing it at 170 °C - 200 °C for 5 - 15 min or curing it under ultraviolet light with a wavelength of 365 nm and an energy of 10 - 80 mW / cm 2 for 5 - 15 min to complete the preparation of the receiving adhesive layer.

[0017] Preferably, in the fourth step, the distance between the monochromatic LED carrier substrate and the receiving substrate is not greater than 10 um, and the distance between the mask and the monochromatic LED carrier substrate ranges from 10 um to 200000 um.

[0018] Preferably, the laser is a solid-state laser with a laser wavelength of 266 nm or an excimer laser with a laser wavelength of 248 nm.

[0019] Preferably, the monochromatic LEDs include red LEDs, green LEDs, and blue LEDs. The monochromatic LED carrier substrates include red carrier substrates, green carrier substrates, and blue carrier substrates. The transfer marks include red marks, green marks, and blue marks.

[0020] Preferably, in step six, according to steps four and five, align one of the red marks on the red carrier substrate with the mark mask hole on the mask. After the alignment is completed, place a laser above the mask. The laser spot emitted by the laser follows the movement of the galvanometer scanner, so that the laser spot completes a surface scan on the mask, so that the red LEDs and the red marks are transferred onto the receiving substrate.

[0021] Preferably, after step six, the method further includes:

[0022] Step seven: Replace the red carrier substrate with the green carrier substrate, align one of the green marks on the green carrier substrate with the mark mask hole on the mask, and the projections of the green carrier substrate and the receiving substrate coincide in the vertical direction. After the alignment is completed, move the receiving substrate horizontally by a distance X, and repeat step six, so that the green LEDs and the green marks are transferred onto the receiving substrate;

[0023] Step eight: Replace the green carrier substrate with the blue carrier substrate, align one of the blue marks on the blue carrier substrate with the mark mask hole on the mask, and the projections of the blue carrier substrate and the receiving substrate coincide in the vertical direction. After the alignment is completed, continue to move the receiving substrate horizontally by a distance X, and repeat step six, so that the blue LEDs and the blue marks are transferred onto the receiving substrate;

[0024] Step nine: Repeat steps five to eight until all the monochromatic LED carrier substrates are completely transferred. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1Structural diagram of the red light carrier substrate for the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0027] Figure 2 Structural diagram of the green light carrier substrate for the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0028] Figure 3 Structural diagram of the blue light carrier substrate for the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0029] Figure 4 Structural diagram of the mask for the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0030] Figure 5 Structural diagram of the receiving substrate for the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0031] Figure 6 Schematic diagram of the transfer state in step six of the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0032] Figure 7 Schematic diagram of the transfer state in step seven of the massive transfer method of micro-LED chips provided by the embodiments of the present invention;

[0033] Figure 8 Schematic diagram of the transfer state in step eight of the massive transfer method of micro-LED chips provided by the embodiments of the present invention.

[0034] Explanation of reference numerals:

[0035] Red light carrier substrate 1 Carrier substrate 11 Photosensitive adhesive layer 12 Red light LED 13 Red light mark 14 Green light carrier substrate 2 Green light LED 23 Green light mark 24 Blue light carrier substrate 3 Blue light LED 33 Blue light mark 34 Mask 4 Light - impermeable layer 41 Light - transmissive layer 42 Mask pattern 43 Receiving substrate 5 Receiving adhesive layer 6

[0036] The present invention will be described in detail below with reference to the accompanying drawings and the description of the drawings. Detailed implementation manners

[0037] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the embodiments of the present invention and should not be construed as limiting the present invention.

[0038] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the embodiments of the present invention and for simplification, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0039] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0040] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0041] In one embodiment of the present invention, a method for mass transfer of micro-LED chips, the method comprising the following steps:

[0042] As Figure 1 、 Figure 2 、 Figure 3 shown, Step 1: Provide a plurality of carrier substrates 11, a plurality of monochromatic LEDs, and a plurality of transfer marks. The monochromatic LEDs and the transfer marks are temporarily bonded to the corresponding carrier substrates 11 through a photosensitive adhesive layer 12 to form a plurality of monochromatic LED carrier substrates;

[0043] Wherein, the LEDs include red LEDs 13, green LEDs 23, and blue LEDs 33. The monochromatic LED carrier substrates include a red carrier substrate 1, a green carrier substrate 2, and a blue carrier substrate 3. The transfer marks include a red mark 14, a green mark 24, and a blue mark 34;

[0044] Specifically, in Step 1, for the massive transfer of micro-LED chips, generally, the arrangement of monochromatic chips needs to be converted into the arrangement of RGB three-color chips. The RGB three-color chips are respectively a red LED chip, a green LED chip, and a blue LED chip. Therefore, according to the color of the chips, three carrier substrates 11 need to be prepared. The LED chips of a single color are bonded to the corresponding carrier substrate 11 through the photosensitive adhesive layer 12 to form a red light carrier substrate 1, a green light carrier substrate 2, and a blue light carrier substrate 3.

[0045] Meanwhile, the photosensitive adhesive layer 12 has photosensitivity and can be decomposed under the irradiation of laser to generate corresponding thrust, so that the LED chips on the carrier substrate 11 are transferred to the corresponding receiving substrate 5 to complete the massive transfer of micro-LED chips.

[0046] Meanwhile, to further improve the transfer efficiency and the utilization rate of LED chips, a transfer mark is introduced in this embodiment. The transfer mark is specifically a cross-shaped structure to facilitate the distinction between the LED chips and the transfer mark.

[0047] It should be noted that before the step of temporarily bonding the monochromatic LED and the transfer mark to the corresponding carrier substrate 11 through the photosensitive adhesive layer 12, a substrate is provided at the bottom of the monochromatic LED. Because during the preparation of the monochromatic LED, epitaxial growth needs to be carried out on the substrate to obtain the monochromatic LED. Therefore, during the bonding process, the monochromatic LED will be bonded to the carrier substrate 11 together with the substrate. At this time, the substrate is on the side of the monochromatic LED away from the carrier substrate 11. After the bonding is completed, the substrate needs to be peeled off from the monochromatic LED to facilitate the subsequent massive transfer process.

[0048] As Figure 4 shown in the figure, Step 2: Provide a mask 4. The mask 4 is provided with a number of LED mask holes corresponding to the LEDs and a mark mask hole corresponding to the transfer mark.

[0049] Meanwhile, the number of LED mask holes on the mask 4 is determined according to the sizes of the receiving substrate 5 and the carrier substrate 11 and the number of RGB three-color chips carried. At the same time, the ratio of the LED mask holes to the mark mask hole on the mask 4 is equal to the ratio of the monochromatic LEDs to the transfer marks on the receiving substrate, and the position of the mark mask hole on the mask 4 is the same as the position of the transfer mark on the carrier substrate 11 to ensure that after several chip massive transfer processes, all the LED chips on the monochromatic LED carrier substrate can be transferred to the receiving substrate 5.

[0050] As Figure 5 shown in the figure, Step 3: Provide a receiving substrate 5 and prepare a receiving adhesive layer 6 on the receiving substrate 5.

[0051] Specifically, the receiving substrate 5 is used to receive the transferred LED chips, and there are several receiving substrates 5. The number of receiving substrates 5 is determined according to the number of LEDs on the monochromatic LED carrier substrate. The receiving adhesive layer 6 is used to fix the transferred monochromatic LEDs. During the mass transfer process, the photosensitive adhesive layer 12 is heated to generate a thrust force. Under the action of the thrust force, the monochromatic LEDs bonded to the carrier substrate 11 are pushed towards the side of the receiving substrate 5, so that the monochromatic LEDs fall onto the receiving substrate 5, completing the mass transfer process.

[0052] Step Four: Arrange the mask 4, the monochromatic LED carrier substrate, and the receiving substrate 5 from top to bottom. Among them, the receiving adhesive layer 6 is disposed opposite to the monochromatic LEDs. The mask 4 is fixedly arranged, and the projections of the monochromatic LED carrier substrate and the receiving substrate 5 in the vertical direction coincide.

[0053] Specifically, in this step, the mask 4 needs to be arranged above the monochromatic LED carrier substrate, so that the laser spot emitted by the laser can pass through the mask pattern on the mask 4 and act on the photosensitive adhesive layer 12. The receiving substrate 5 is arranged below the monochromatic LED carrier substrate, and the receiving adhesive layer 6 is disposed opposite to the monochromatic LEDs. The purpose is to ensure that the monochromatic LEDs can fall from the carrier substrate 11 onto the receiving substrate 5 under the action of the thrust force generated by the decomposition of the photosensitive adhesive layer 12, completing the transfer of the chips.

[0054] At the same time, the projections of the monochromatic LED carrier substrate and the receiving substrate 5 in the vertical direction coincide, so as to ensure that the receiving substrate 5 can successfully receive the transferred monochromatic LEDs during the transfer of the monochromatic LEDs.

[0055] It should be noted that during the mass transfer of micro-LED chips, a carrying platform needs to be provided. The carrying platform is not shown in detail in the drawings. The mask 4, the monochromatic LED carrier substrate, and the receiving substrate 5 are installed on the carrying platform from top to bottom. Among them, the mask 4 is fixed on the carrying platform to limit and lock it to prevent relative displacement between it and the carrying platform. The monochromatic LED carrier substrate is clamped by a manipulator and is located between the mask 4 and the receiving substrate 5. The receiving substrate 5 is horizontally slidably installed on the carrying platform and can move horizontally on the carrying platform. And in this step, the monochromatic LED carrier substrate is the red light carrier substrate 1.

[0056] Step Five: Align one of the transfer marks on the monochromatic LED carrier substrate with the mark mask hole on the mask 4.

[0057] Specifically, a manipulator is used to place the monochromatic LED carrier substrate between the mask 4 and the receiving substrate 5. At the same time, due to the different fixed positions of the mask 4, the position of the monochromatic LED carrier substrate is finely adjusted so that one of the transfer marks on the monochromatic LED carrier substrate coincides with the marked mask hole on the mask 4 in the vertical direction, and the shapes of the transfer mark and the marked mask hole match, both being cross-shaped structures. The transfer mark and the marked mask hole arranged in a cross-shaped structure ensure that there is no relative displacement and relative angle between the monochromatic LED carrier substrate and the receiving substrate 5 during the alignment process, and ensure that the projections of the monochromatic LED carrier substrate and the receiving substrate 5 coincide in the vertical direction.

[0058] As Figure 6 shown, in step six, after the alignment is completed, a laser is arranged above the mask 4. The laser spot emitted by the laser follows the movement of the galvanometer so that the laser spot completes a surface scan on the mask 4, so that the monochromatic LED and the transfer mark are transferred onto the receiving substrate 5;

[0059] Specifically, this laser is used to provide the irradiation laser required for the decomposition of the photosensitive adhesive layer 12. During the actual transfer process, the laser is arranged above the mask 4. Through the relative movement between the laser spot emitted by the laser and the mask 4, the laser spot completes a surface scan on the mask 4, so that the laser spot can pass through the mask pattern 43 and pass through the light-transmitting layer 42 to act on the photosensitive adhesive layer 12 on the carrier substrate 11, causing it to decompose and generate a thrust force to push the monochromatic LED onto the receiving substrate 5;

[0060] It can be understood that through the relative movement between the laser spot emitted by the laser and the mask 4, the laser spot completes a surface scan on the mask 4. Therefore, during the actual transfer process, a sliding mechanism can be used to push the laser to move horizontally above the mask 4 to complete the surface scan, or the laser can be fixed and the bearing platform can be pushed so that the laser spot emitted by the laser completes the surface scan, so that the monochromatic LED and the transfer mark are transferred onto the receiving substrate 5;

[0061] It should be noted that the monochromatic LED in step six is a red LED 13, and the transfer mark is a red mark 14.

[0062] As Figure 7 shown, in step seven, replace the red light carrier substrate 1 with the green light carrier substrate 2, align one of the green marks 24 on the green light carrier substrate 2 with the marked mask hole on the mask 4, and the projections of the green light carrier substrate 2 and the receiving substrate 5 coincide in the vertical direction. After the alignment is completed, move the green light carrier substrate 2 horizontally by a distance X, and repeat step six to transfer the green LED 23 and the green mark 24 onto the receiving substrate 5;

[0063] Specifically, since this application needs to convert the arrangement of monochromatic chips into the arrangement of RGB three-color chips, without changing the mask 4 and the receiving substrate 5, the monochromatic chips of other colors are replaced, and the above steps of transferring the mark and aligning the mark mask holes are repeated. At the same time, the process of the laser emitting laser spots and completing the area scan is repeated, so that the green LED 23 and the green mark 24 are transferred onto the receiving substrate 5. And in this step, a red LED 13, a green LED 23, a red mark 14, and a green mark 24 are adhered to the receiving substrate 5 through an adhesive layer 6;

[0064] At the same time, in this step, after the transfer mark is aligned with the mark mask hole, at this time, a red LED 13 has been adhered to the adhesive layer 6 corresponding to the lower part of the green LED 23 to be transferred, and a red mark 14 has been adhered to the adhesive layer 6 corresponding to the lower part of the green mark 24 to be transferred. Therefore, it is necessary to control the receiving substrate 5 to translate a distance X to one side, so that the green LED 23 and the red LED 13, and the green mark 24 and the red mark 14 are staggered, so that the green LED 23 and the green mark 24 are correspondingly transferred to one side of the red LED 13 and the red mark 14.

[0065] As Figure 8 shown, in step eight, replace the green carrier substrate 2 with the blue carrier substrate 3, align one of the blue marks 34 on the blue carrier substrate 3 with the mark mask hole on the mask 4, and the projections of the blue carrier substrate 3 and the receiving substrate 5 coincide in the vertical direction. After the alignment is completed, continue to horizontally move the blue carrier substrate 3 a distance X, and repeat step six, so that the blue LED 33 and the blue mark 34 are transferred onto the receiving substrate 5;

[0066] This step is similar to step seven. Without changing the mask 4 and the receiving substrate 5, the monochromatic chips of other colors are replaced, and the above steps of transferring the mark and aligning the mark mask holes are repeated. At the same time, the process of the laser emitting laser spots and completing the area scan is repeated, so that the blue LED 33 and the blue mark 34 are transferred onto the receiving substrate 5. And in this step, a red LED 13, a green LED 23, a blue LED 33, a red mark 14, a green mark 24, and a blue mark 34 are adhered to the receiving substrate 5 through an adhesive layer 6;

[0067] Meanwhile, in this step, after the transfer marks are aligned with the mark mask holes, the green LED 23 to be transferred has adhered to the corresponding adhesive layer 6 below it, and the green mark 24 has adhered to the corresponding adhesive layer 6 below the blue mark 34 to be transferred. Therefore, it is necessary to control the receiving substrate 5 to translate a distance of X to one side, which has been translated a distance of 2X compared to the initial position of the receiving substrate 5, so as to stagger the blue LED 33 from the green LED 23 and the blue mark 34 from the green mark 24, so that the blue LED 33 and the blue mark 34 are correspondingly transferred to one side of the green LED 23 and the green mark 24;

[0068] It is worth mentioning that in the above steps seven and eight, the green carrier substrate 2 replaces the red carrier substrate 1, and the blue carrier substrate 3 replaces the green carrier substrate 2. Therefore, during the transfer of monochromatic LEDs, the relative positions of the red carrier substrate 1, the green carrier substrate 2, and the blue carrier substrate 3 with respect to the mask 4 remain unchanged and the orientations are the same.

[0069] Step nine: Repeat steps five to eight until all the monochromatic LED carrier substrates are transferred;

[0070] After the above steps five to eight, the receiving substrate 5 is now covered with RGB three-color chips and corresponding transfer marks. However, there may still be many monochromatic LED chips left on the monochromatic LED carrier substrate. At this time, the receiving substrate 5 can be replaced and the above steps can be repeated until all the monochromatic LED carrier substrates are transferred.

[0071] In this embodiment, several of the monochromatic LEDs are arranged in a rectangular array on the photosensitive adhesive layer 12, and a transfer mark area is reserved on the photosensitive adhesive layer 12. Several of the transfer marks are arranged in a rectangular array within the transfer mark area;

[0072] Specifically, by reserving the transfer mark area, it is more convenient to perform the monochromatic LEDs on the monochromatic LED carrier substrate, and during the transfer, the relative positions of the monochromatic LEDs and the transfer marks will not change, so as to improve the efficiency of mass transfer.

[0073] In this embodiment, both the carrier substrate 11 and the receiving substrate 5 are made of sapphire or quartz, and the carrier substrate 11 and the receiving substrate 5 have the same size and dimensions;

[0074] Specifically, sapphire or quartz has the characteristics of being resistant to laser irradiation and having high transparency, so that the laser spot can pass through the carrier substrate 11 and act on the photosensitive adhesive layer 12. At the same time, the carrier substrate 11 and the receiving substrate 5 have the same size and dimensions to ensure that the projections of the carrier substrate 11 and the receiving substrate 5 in the vertical direction coincide.

[0075] In this embodiment, in the first step, the step of temporarily bonding the monochromatic LED and the transfer mark to the corresponding carrier substrate 11 through the photosensitive adhesive layer 12 includes: preparing a photosensitive adhesive layer 12 with a thickness of 3 um - 20 um on the carrier substrate 11 by means of spin coating, spraying, or film laminating, fitting the monochromatic LED, the transfer mark and the carrier substrate 11 together, putting them into a press and applying a pressure of 100 kg - 750 kg, and keeping the temperature constant at 150 - 230 °C for 1 - 3 h to complete the temporary bonding of the monochromatic LED, the transfer mark and the carrier substrate 11.

[0076] In this embodiment, in the second step, the mask 4 includes a light-transmitting layer 42 and an opaque layer 41 deposited on the light-transmitting layer 42. The opaque layer 41 is provided with a mask pattern 43 to expose a part of the light-transmitting layer 42. The mask pattern 43 is composed of a plurality of LED mask holes and a mark mask hole. The light-transmitting layer 42 is made of quartz material, and the opaque layer 41 is a chromium layer;

[0077] Specifically, in the second step, the deposition process of the mask 4 is the same as that of the photolithography mask 4, that is, an opaque layer 41 is deposited on the light-transmitting layer 42, a layer of photoresist is coated on the opaque layer 41, and then it is exposed, developed after exposure, and dried after development to form a mask pattern 43 on the opaque layer 41. The mask pattern 43 includes a plurality of LED mask holes and a mark mask hole, and the LED mask holes are rectangularly distributed on the mask;

[0078] Specifically, the chromium layer has the property of light impermeability, while the quartz material has the characteristic of high light transmittance, so as to ensure that when the laser emits a laser spot, the laser spot can only act on the monochromatic LED and the transfer mark corresponding to the mask pattern 43. Through the block of the opaque layer 41, the laser spot is prevented from acting on other monochromatic LEDs and transfer marks.

[0079] In this embodiment, in the third step, the step of preparing the receiving adhesive layer 6 on the receiving substrate 5 includes: preparing a PDMS layer with a thickness of 1 um - 10 um on the receiving substrate 5 by means of spin coating or spraying, and then putting it into an oven and curing it at 170 °C - 200 °C for 5 - 15 min or curing it under ultraviolet light with a wavelength of 365 nm and an energy of 10 - 80 mW / cm 2 for 5 - 15 min to complete the preparation of the receiving adhesive layer 6;

[0080] Among them, the material of the receiving adhesive layer 6 is PDMS, which is used to stably receive the transferred LED and transfer mark.

[0081] In this embodiment, in the fourth step, the distance between the monochromatic LED carrier substrate and the receiving substrate 5 is not greater than 10 μm, and the distance between the mask 4 and the monochromatic LED carrier substrate ranges from 10 μm to 200,000 μm;

[0082] Specifically, the distance between the monochromatic LED carrier substrate and the receiving substrate 5 is not greater than 10 μm, and the purpose is to shorten the distance between the monochromatic LED transferred from the carrier substrate 11 to the receiving substrate 5, which can avoid the error generated during the transfer of the monochromatic LED to a certain extent. The distance between the mask 4 and the monochromatic LED carrier substrate can be changed according to the laser characteristics and installation position of the laser.

[0083] In this embodiment, the laser is a solid-state laser with a laser wavelength of 266 nm or an excimer laser with a laser wavelength of 248 nm.

[0084] In this embodiment, in the seventh and eighth steps, the distance X is the sum of the pitch between two adjacent monochromatic LEDs and the width of the LED;

[0085] Specifically, the distance X can be changed according to the factory requirements and processes of RGB three-color chip products.

[0086] In summary, the method for massive transfer of micro-LED chips in the above embodiments of the present invention realizes the massive transfer of micro-LED chips by designing transfer marks corresponding to different monochromatic LEDs and the alignment method of the corresponding mask 4 and the monochromatic LED carrier substrate. By designing transfer marks, the subsequent testing and packaging processes of micro-LED chips are simplified and facilitated. At the same time, through the definition of different transfer marks, the high utilization rate of chip transfer is achieved, and the transfer of micro-LED edge chips can be realized to overcome the defects existing in the transfer of rectangular small areas.

[0087] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for mass transfer of micro-LED chips, characterized in that, The method includes the following steps: Step 1: Provide a plurality of carrier substrates, a plurality of monochromatic LEDs, and a plurality of transfer marks. Temporarily bond the monochromatic LEDs and the transfer marks to the corresponding carrier substrates through a photosensitive adhesive layer to form a plurality of monochromatic LED carrier substrates; Step 2: Provide a mask, on which there are a plurality of LED mask holes corresponding to the monochromatic LEDs and a mark mask hole corresponding to the transfer mark; Step 3: Provide a receiving substrate and prepare a receiving adhesive layer on the receiving substrate; Step 4: Arrange the mask, the monochromatic LED carrier substrate, and the receiving substrate from top to bottom. Among them, the receiving adhesive layer is arranged opposite to the monochromatic LED, the mask is fixedly arranged, and the projections of the monochromatic LED carrier substrate and the receiving substrate in the vertical direction coincide; Step 5: Align one of the transfer marks on the monochromatic LED carrier substrate with the mark mask hole on the mask; Step 6: After the alignment is completed, set a laser above the mask. The laser spot emitted by the laser follows the movement of the galvanometer scanner, so that the laser spot completes a surface scan on the mask, so that the monochromatic LEDs and the transfer marks are transferred to the receiving substrate.

2. The method for mass transfer of micro-LED chips according to claim 1, wherein A plurality of the monochromatic LEDs are arranged in a rectangular array on the photosensitive adhesive layer, a transfer mark area is reserved on the photosensitive adhesive layer, and a plurality of the transfer marks are arranged in a rectangular array in the transfer mark area.

3. The method for massive transfer of micro-LED chips according to claim 1, wherein In Step 1, the step of temporarily bonding the monochromatic LEDs and the transfer marks to the corresponding carrier substrates through the photosensitive adhesive layer includes: preparing a photosensitive adhesive layer with a thickness of 3um - 20um on the carrier substrate by means of spin coating, spraying, or film pasting, fitting the monochromatic LEDs, the transfer marks and the carrier substrate together, putting them into a press and applying a pressure of 100kg - 750kg, and keeping the temperature constant at 150 - 230°C for 1 - 3h to complete the temporary bonding of the monochromatic LEDs, the transfer marks and the carrier substrate.

4. The method for mass transfer of micro-LED chips according to claim 1, wherein, In Step 2, the mask includes a light-transmitting layer and an opaque layer deposited on the light-transmitting layer. The opaque layer is provided with a mask pattern to expose a part of the light-transmitting layer. The plurality of LED mask holes and one mark mask hole form the mask pattern. The light-transmitting layer is made of quartz material, and the opaque layer is a chromium layer.

5. The method for massive transfer of micro-LED chips according to claim 1, characterized in that, In the third step, the step of preparing the receiving adhesive layer on the receiving substrate includes: preparing a PDMS layer with a thickness of 1 um - 10 um on the receiving substrate by spin coating or spraying, and then putting it into an oven for curing at 170 °C - 200 °C for 5 - 15 min or curing under ultraviolet light with a wavelength of 365 nm and an energy of 10 - 80 mW / cm 2 for 5 - 15 min to complete the preparation of the receiving adhesive layer.

6. The method for massive transfer of micro-LED chips according to claim 1, wherein In Step 4, the distance between the monochromatic LED carrier substrate and the receiving substrate is not greater than 10um, and the distance between the mask and the monochromatic LED carrier substrate ranges from 10um to 200000um.

7. The method for mass transfer of micro-LED chips according to claim 1, wherein The laser is a solid-state laser with a laser wavelength of 266nm or an excimer laser with a laser wavelength of 248nm.

8. The method for mass transfer of the micro-LED chip according to claim 1, wherein The monochromatic LEDs include red LEDs, green LEDs, and blue LEDs. The monochromatic LED carrier substrates include red carrier substrates, green carrier substrates, and blue carrier substrates. The transfer marks include red marks, green marks, and blue marks.

9. The method for mass transfer of micro-LED chips according to claim 8, wherein In the sixth step, according to the fourth and fifth steps, align one of the red light markers on the red light carrier substrate with the marker mask hole on the mask. After the alignment is completed, a laser is arranged above the mask, and the laser spot emitted by the laser follows the movement of the galvanometer mirror, so that the laser spot completes a surface scan on the mask, so as to transfer the red light LED and the red light marker to the receiving substrate.

10. The method for mass transfer of the micro-LED chip according to claim 9, wherein After the sixth step, the method further includes: Step 7: Replace the red light carrier substrate with the green light carrier substrate, align one of the green light markers on the green light carrier substrate with the marker mask hole on the mask, and the projections of the green light carrier substrate and the receiving substrate coincide in the vertical direction. After the alignment is completed, move the receiving substrate horizontally by a distance X, and repeat step 6 to transfer the green light LED and the green light marker to the receiving substrate; Step 8: Replace the green light carrier substrate with the blue light carrier substrate, align one of the blue light markers on the blue light carrier substrate with the marker mask hole on the mask, and the projections of the blue light carrier substrate and the receiving substrate coincide in the vertical direction. After the alignment is completed, continue to move the receiving substrate horizontally by a distance X, and repeat step 6 to transfer the blue light LED and the blue light marker to the receiving substrate; Step 9: Replace the receiving substrate and repeat steps 5 to 8 until all the monochromatic LED carrier substrates are transferred.

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