Chip transfer method

Abstract

The application relates to a chip transfer method. The chip transfer method comprises the following steps: providing a growth substrate with a plurality of LED chips formed on a surface; transferring the LED chips to a temporary substrate, the LED chips being provided with exposed first surfaces away from one side of the temporary substrate; forming a support layer connected with the LED chips on the temporary substrate, and forming a through channel in the temporary substrate; and applying a force to the first surfaces so that each LED chip is transferred to a target substrate through the through channel. By using the above chip transfer method, the gravity of the LED chips is utilized to realize the transfer to the target substrate, and the yield of the chip transfer can be greatly improved. Furthermore, by using the above chip transfer process, the position of the through channel is corresponded to a pre-repaired target position, and by applying the force to the LED chips, the repair of the missing chips at the target position can also be realized.

Description

Technical Field

[0001] This application relates to the field of chip mass transfer technology, and in particular to a chip transfer method. Background Technology

[0002] Micro-LED (Micro Light Emitting Diode) is an emerging display technology. Compared with conventional display technologies, displays based on Micro-LED technology have the characteristics of fast response speed, self-illumination, high contrast, long lifespan, and high photoelectric efficiency.

[0003] Mass transfer technology is a core technology in the Micro-LED industry, using high-precision equipment to transfer a large number of Micro-LED chips onto a target substrate or circuit. Cost, yield, and precision are key factors for successful mass transfer.

[0004] Currently, mass transfer technologies for Micro-LEDs are categorized into several technical schools based on their underlying principles, including electrostatic transfer, van der Waals force, magnetic transfer, laser selective transfer, fluid transfer, and direct transfer. After these methods transfer the chip onto the substrate, gaps can easily appear at the target location, affecting the chip transfer yield and necessitating the repair of any missing chips at the target location. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a chip transfer method, which aims to solve the problem that the chip transfer process affects the chip transfer yield in the prior art.

[0006] A chip transfer method includes the following steps:

[0007] A growth substrate with multiple LED chips formed on its surface is provided;

[0008] The LED chip is transferred to the transient substrate, and the side of the LED chip away from the transient substrate has an exposed first surface;

[0009] A support layer connecting the LED chip is formed on the transient substrate, and a through channel is formed in the transient substrate;

[0010] A force is applied to the first surface to transfer each LED chip to the target substrate through the through-channel.

[0011] Using the chip transfer method described in this application, LED chips are transferred to a transient substrate. The side of the LED chip away from the transient substrate has an exposed first surface. By forming a support layer connecting the LED chips on the transient substrate and forming a through-channel in the transient substrate, and then applying a force to the first surface, each LED chip is transferred to the target substrate through the through-channel. The transfer to the target substrate is achieved by utilizing the gravity of the LED chip itself, which can greatly improve the chip transfer yield. Furthermore, by using the chip transfer process described in this application, by aligning the position of the through-channel with the target position to be repaired and by applying a force to the LED chip, the repair of missing chips at the target position can also be achieved.

[0012] Optionally, each LED chip includes an epitaxial structure, a first electrode, and a second electrode, with the first and second electrodes located on the side of the epitaxial structure away from the growth substrate. After the step of transferring the LED chip to the transient substrate, the epitaxial structure is located on the side of the first and second electrodes away from the transient substrate, and the epitaxial structure has a first surface. The aforementioned light-emitting device can be a flip-chip structure, thus eliminating the need for leads to connect the electrodes to the display backplane, which helps to reduce the distance between the light-emitting devices and thereby improves the PPI of the display panel.

[0013] Optionally, the step of transferring the LED chip to the transient substrate includes: bonding the LED chip to the transient substrate using an adhesive layer, such that the growth substrate is located on the side of the LED chip away from the transient substrate; and peeling off the growth substrate to expose the first surface. The adhesive layer can be a conventional photodegradable adhesive or thermal degradable adhesive, formed by a coating process to cover the transient substrate. The adhesive layer can be removed subsequently by heat treatment or light irradiation, making the process simple and easy to implement.

[0014] Optionally, prior to the step of forming a support layer on the first surface of the connection portion on the transient substrate, the chip transfer method further includes the step of removing the adhesive layer located between adjacent LED chips on the transient substrate. By removing the adhesive layer between adjacent LED chips, the support layer can be directly connected to the transient substrate in the subsequent step of forming the support layer, thereby enabling the support layer to be more firmly connected to the transient substrate.

[0015] Optionally, the LED chip has a first side surface surrounding the first surface. In the step of forming a support layer for connecting the LED chip on the transient substrate, the support layer connects a portion of the first surface and / or at least a portion of the first side surface. The connection method between the support layer and the LED chip in this application is flexible. For example, the support layer can be connected only to the first surface of the LED chip, only to the first side surface of the LED chip, or simultaneously to both the first surface and the first side surface of the LED chip.

[0016] Optionally, the step of forming a support layer on the first surface of the connection portion on the transient substrate includes: forming a support preparation layer encapsulating the LED chip on the transient substrate; patterning the support preparation layer located on the first surface to expose at least a portion of the first surface, with the remaining support preparation layer constituting the support layer. By first forming the support preparation layer encapsulating the LED chip and then etching to expose the LED chip with a stress-bearing surface, the formed support layer can be stably connected to the transient substrate. The process is simple and easy to implement.

[0017] Optionally, the step of patterning the support preparation layer on the first surface includes: etching the support preparation layer on the first surface so that the remaining support preparation layer surrounds the edge of the first surface. By forming a support layer that surrounds and connects to the edge of the first surface of the LED chip, not only can the support layer be more firmly connected to the transient substrate, but a larger exposed area can also be provided in the first surface, resulting in a larger force-bearing area. Consequently, the LED chip can be transferred to the target substrate with a smaller force in the subsequent process.

[0018] Optionally, a support preparation layer can be formed on the transient substrate using a PECVD process. Compared to other deposition processes in the prior art, the PECVD (plasma-enhanced chemical vapor deposition) process can effectively avoid the impact on device performance caused by the deposited material entering the epitaxial structure of the LED chip.

[0019] Optionally, the material forming the support preparation layer includes one or more of silicon oxide, silicon nitride, and silicon oxynitride. Using the above materials as the material for subsequently forming the support layer not only enables the support layer to be firmly connected to the transient substrate, but also has mature technology and low cost.

[0020] Optionally, the step of forming through channels in the transient substrate includes: patterning the transient substrate to form multiple through channels corresponding one-to-one with LED chips, wherein the minimum cross-sectional dimension of each through channel is larger than the maximum cross-sectional dimension of each LED chip in a direction parallel to the transient substrate. When an external force is applied, the LED chip separates from the support layer and is transferred to the target substrate due to gravity. By forming the aforementioned through channels corresponding one-to-one with the LED chip, the LED chip can be prevented from flipping during its fall, greatly improving the transfer yield.

[0021] Optionally, the transient substrate includes any one of a silicon substrate, a silicon carbide substrate, and a gallium arsenide substrate. Compared with substrates such as sapphire and lift-off substrates in the prior art, the transient substrates of the above-mentioned materials have lower hardness. Using the above-mentioned optional substrate types can reduce the difficulty of etching to form the above-mentioned through-channels.

[0022] Optionally, the depth of the through-channel is H1, and the height of the LED chip in the depth direction of the through-channel is H2, where H1 > H2. During the chip transfer process at a predetermined position on the target substrate, since LED chips may already be installed at other positions on the target substrate corresponding to different through-channels, by ensuring that the depth of the through-channel and the height of the LED chip satisfy the above relationship, it is possible to avoid affecting chips at other positions when repairing chips at the predetermined position.

[0023] Optionally, the step of applying a force to the first surface to transfer each LED chip to the target substrate through the through-channel includes: providing a target substrate, one side surface of which has a target area; placing a transient substrate on the target substrate such that the LED chips are located on the side of the transient substrate away from the target substrate and correspond to the target area; and applying a force to the first surface to transfer the LED chips to the target area through the through-channel. Conventional chip transfer processes in the prior art may result in gaps in some target areas on the target substrate, meaning that the LED chips corresponding to the target positions are not transferred. In such cases, the above steps can be used to repair the chips. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the substrate structure after forming an epitaxial structure on a growth substrate in a chip transfer method provided in one embodiment of this application;

[0025] Figure 2 In order to be in Figure 1 A schematic diagram of the substrate structure after an ITO conductive layer is formed on the surface of the N-type semiconductor layer in the epitaxial structure shown.

[0026] Figure 3 In order to be in Figure 2 The diagram shows the structure of the substrate after a reflective layer covering the epitaxial structure is formed on the growth substrate, and through-holes are formed in the reflective layer that penetrate to the ITO conductive layer and the P-type semiconductor layer, respectively.

[0027] Figure 4 In order to be in Figure 3 The diagram shows the structure of the substrate after forming a first lead-out portion connecting the ITO conductive layer and a second lead-out portion connecting the P-type semiconductor layer in the lead-out holes.

[0028] Figure 5 In order to be in Figure 4 The diagram shows the structure of the substrate after the adhesive layer is applied to the transient substrate.

[0029] Figure 6 To pass Figure 5 The diagram shows the structure of the substrate after the adhesive layer bonds the LED chip to the transient substrate.

[0030] Figure 7 For stripping Figure 6 The diagram shows the structure of the substrate after the growth substrate has been exposed to expose the first surface.

[0031] Figure 8 To remove Figure 7 The diagram shows the structure of the substrate behind the adhesive layer between adjacent LED chips on the transient substrate.

[0032] Figure 9 In order to be in Figure 8 The diagram shows the structure of the substrate after the support preparation layer encapsulating the LED chip is formed on the transient substrate.

[0033] Figure 10 To be located Figure 9 A schematic diagram of the structure of the substrate after the support preparation layer on the first surface is patterned to form the support layer;

[0034] Figure 11 To be Figure 10 The diagram shows a schematic of the structure of the substrate after the transient substrate is patterned to form a through-channel.

[0035] Figure 12 To be Figure 11 The diagram shows the structure of the substrate after the adhesive layer has been removed.

[0036] Figure 13 To be Figure 12 The diagram shows the structure of the LED chip mounted on one side of the target substrate via a support layer.

[0037] Figure 14 To Figure 13 The diagram shows a structure in which a force is applied to the first surface to transfer each LED chip through a through-channel to the target substrate.

[0038] Figure 15 In order to make Figure 13 The diagram shows the structure of the substrate after the LED chip is located on the side of the transient substrate away from the target substrate and corresponds to the target area.

[0039] Figure 16 To Figure 15 The diagram shows the structure of the substrate after a force is applied to the first surface to transfer the LED chip to the target area through the through-channel.

[0040] Explanation of reference numerals in the attached figures:

[0041] 10 - LED chip; 101 - First surface; 110 - Epitaxial structure; 111 - N-type semiconductor layer; 112 - Active layer; 113 - P-type semiconductor layer; 120 - First electrode; 121 - ITO conductive layer; 122 - First lead-out portion; 130 - Second electrode; 140 - Reflective layer; 20 - Growth substrate; 30 - Transient substrate; 310 - Through-channel; 40 - Adhesive layer; 50 - Support layer; 510 - Support preparation layer; 60 - Target substrate; 610 - Target area. Detailed Implementation

[0042] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0044] As described in the background section, currently, the mass transfer technology for Micro-LEDs, after transferring the chip onto the substrate, is prone to creating vacancies at the target location, which affects the chip transfer yield and requires repair of missing chips at the target location.

[0045] Therefore, this application aims to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in subsequent embodiments.

[0046] The inventors of this application have researched the above-mentioned problems and proposed a chip transfer method, including the following steps:

[0047] A growth substrate with multiple LED chips formed on its surface is provided;

[0048] The LED chip is transferred to the transient substrate, and the side of the LED chip away from the transient substrate has an exposed first surface;

[0049] A support layer for connecting LED chips is formed on a transient substrate, and a through channel is formed in the transient substrate;

[0050] A force is applied to the first surface to transfer each LED chip to the target substrate through the through-channel.

[0051] Using the chip transfer method described in this application, LED chips are transferred to a transient substrate. The side of the LED chip away from the transient substrate has an exposed first surface. By forming a support layer connecting the LED chips on the transient substrate and forming a through-channel in the transient substrate, and then applying a force to the first surface, each LED chip is transferred to the target substrate through the through-channel. The transfer to the target substrate is achieved by utilizing the gravity of the LED chip itself, which can greatly improve the chip transfer yield. Furthermore, by using the chip transfer process described in this application, by aligning the position of the through-channel with the target position to be repaired and by applying a force to the LED chip, the repair of missing chips at the target position can also be achieved.

[0052] Exemplary embodiments of the chip transfer method provided according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art.

[0053] First, a growth substrate 20 with multiple LED chips 10 formed on its surface is provided, such as... Figures 1 to 4 As shown.

[0054] In some embodiments, the growth substrate 20 includes, but is not limited to, glass sheets, quartz sheets, gallium arsenide substrates, and sapphire substrates.

[0055] For example, each LED chip 10 includes an epitaxial structure 110, a first electrode 120 and a second electrode 130, the first electrode 120 and the second electrode 130 being located on the side of the epitaxial structure 110 away from the growth substrate 20; after the step of transferring the LED chip 10 to the transient substrate 30, the epitaxial structure 110 is located on the side of the first electrode 120 and the second electrode 130 away from the transient substrate 30, and the epitaxial structure 110 has a first surface 101.

[0056] The LED chip 10 described above can be a Micro-LED chip, a Min-LED (mini light-emitting diode) chip, or a larger LED chip. For example, the LED chip 10 is an OLED (Organic Light-Emitting Diode) chip. Furthermore, this application does not limit the structural type or color type of the LED chip 10; it can be a three-primary-color (red, green, blue) chip or an LED chip of colors other than the three primary colors. The light-emitting device can be a right-mounted structure, a flip-chip structure, a vertical structure, or a horizontal structure. The LED chip 10 with a flip-chip structure does not require leads to connect the electrodes to the display backplane, which helps to reduce the distance between the light-emitting devices, thereby improving the PPI of the display panel.

[0057] In some embodiments of this application, providing a growth substrate 20 on which a plurality of LED chips 10 are formed includes the following steps: forming an epitaxial structure 110 on the growth substrate 20, the epitaxial structure 110 including an N-type semiconductor layer 111, an active layer 112, and a P-type semiconductor layer 113, such as... Figure 1 As shown; a first electrode 120 and a second electrode 130 are formed and respectively connected to the epitaxial structure 110, as follows: Figures 2 to 4 As shown.

[0058] In the above embodiments, the LED chip 10 can be a GaN-based LED. For example, the N-type semiconductor layer 111 is an N-type GaN layer, the active layer 112 is a quantum well layer, and the P-type semiconductor layer 113 is a P-type GaN layer.

[0059] In some embodiments of this application, the step of forming the first electrode 120 and the second electrode 130 respectively connected to the epitaxial structure 110 may include: forming an ITO (indium tin oxide) conductive layer on the surface of the N-type semiconductor layer 111, such as... Figure 2 As shown; a reflective layer 140 covering the epitaxial structure 110 is formed on the growth substrate 20, and through-holes penetrating to the ITO conductive layer 121 and the N-type semiconductor layer 111 are formed in the reflective layer 140, respectively. Figure 3 As shown; a first lead-out portion 122 connecting the ITO conductive layer 121 and a second lead-out portion connecting the N-type semiconductor layer 111 are respectively formed in the lead-out holes, as follows: Figure 4 As shown.

[0060] In the above embodiments, the ITO conductive layer 121 has high conductivity and visible light transmittance. Using the ITO conductive layer 121 as part of the first electrode 120 can improve the luminous brightness of the LED chip 10. For example, the thickness of the ITO conductive layer 121 is...

[0061] In the above embodiments, the reflective layer 140 is used to improve the luminous brightness of the LED chip 10. The reflective layer 140 may have a DBR (distributed Bragg reflection) structure. The DBR structure is typically composed of two materials with different refractive indices arranged alternately, and the optical thickness of each layer is 1 / 4 of the central reflection wavelength. For example, the reflective layer 140 includes alternating layers of silicon oxide and silicon nitride with a thickness of 1 to 4 μm.

[0062] In the above embodiments, a dry etching process can be used to form the first lead-out portion 122 and the second lead-out portion in the reflective layer 140. For example, the reflective layer 140 is composed of alternating layers of silicon oxide and silicon nitride, and the etching gas used in the dry etching process is CF4O2Ar.

[0063] In the above embodiment, the first lead-out portion 122 can serve as part of the first electrode 120, together with the ITO conductive layer 121 constituting the first electrode 120 of the LED chip 10. The second lead-out portion can directly serve as the second electrode 130 of the LED chip 10. The first lead-out portion 122 and the second lead-out portion can be conventional conductive materials in the prior art. For example, the first lead-out portion 122 and the second lead-out portion are formed on the reflective layer 140 using a negative photoresist photolithography process and an etching process. Then, the lead-out electrode is deposited using a vapor deposition process with a thickness of 1 to 4 μm. After removing the photoresist, the first lead-out portion 122 and the second lead-out portion are formed.

[0064] After providing the growth substrate 20 on which the LED chip 10 is formed, the LED chip 10 is transferred to the transient substrate 30. The side of the LED chip 10 away from the transient substrate 30 has an exposed first surface 101, such as... Figures 5 to 7 As shown.

[0065] In some embodiments of this application, the step of transferring the LED chip 10 to the transient substrate 30 includes: bonding the LED chip 10 to the transient substrate 30 using an adhesive layer 40, such that the growth substrate 20 is located on the side of the LED chip 10 away from the transient substrate 30, as shown below. Figure 5 and Figure 6 As shown; the growth substrate 20 is peeled off to expose the first surface 101, as... Figure 7 As shown. The material forming the adhesive layer 40 can be conventional photolytic or thermally degradable adhesives in the prior art. The adhesive layer 40 covering the transient substrate 30 is formed by a coating process. The adhesive layer 40 can be removed in the subsequent heat treatment or light irradiation. The process is simple and easy to implement.

[0066] In the above embodiments, the adhesive layer 40 can be formed on the surface of the transient substrate 30 by a coating process. For example, the adhesive layer 40 is a BCB (benzocyclobutene) adhesive layer.

[0067] The steps described above, in which the LED chip 10 is bonded to the transient substrate 30 via the adhesive layer 40, can be implemented in different ways, thereby allowing the subsequently formed support layer 50 to have different connection methods with the LED chip 10.

[0068] In an optional embodiment, the LED chip 10 has a second surface opposite to the first surface 101 and a first side surface surrounding the first surface 101. The step of bonding the LED chip 10 to the transient substrate 30 by the adhesive layer 40 includes: making the adhesive layer 40 completely cover the second surface and the first side surface of the LED chip 10, and fixing the LED chip 10 to the transient substrate 30 by the adhesive layer 40 on the second surface and the first side surface.

[0069] In the above embodiment, after the growth substrate 20 is peeled off, since only the first surface 101 of the LED chip 10 is exposed, the subsequently formed support layer 50 can be connected only to the first surface 101.

[0070] In the above embodiments, an adhesive material can be coated on the surface of the transient substrate 30, and one side of the LED chip 10 with the second surface can be inserted into the adhesive material so that the first side of the LED chip 10 is completely wrapped by the adhesive material. Then, by curing the adhesive material to form an adhesive layer 40 that connects the transient substrate 30 and the LED chip 10, the adhesive layer 40 can completely cover the second surface and the first side of the LED chip 10.

[0071] In another alternative embodiment, the LED chip 10 has a second surface opposite to the first surface 101 and a first side surface surrounding the first surface 101. The step of bonding the LED chip 10 to the transient substrate 30 by the adhesive layer 40 includes: making the adhesive layer 40 completely cover the second surface of the LED chip 10 and partially cover the first side surface of the LED chip 10, and fixing the LED chip 10 to the transient substrate 30 by the adhesive layer 40 on the second surface and the first side surface.

[0072] In the above embodiment, after the growth substrate 20 is peeled off, since the first surface 101 and part of the first side surface of the LED chip 10 are exposed, the subsequently formed support layer 50 can be connected to the first surface 101 and the first side surface at the same time.

[0073] In the above embodiments, an adhesive material can be coated on the surface of the transient substrate 30, and one side of the LED chip 10 with the second surface can be inserted into the adhesive material, so that the first side of the LED chip 10 is partially wrapped by the adhesive material. Then, by curing the adhesive material to form an adhesive layer 40 connecting the transient substrate 30 and the LED chip 10, the adhesive layer 40 can completely cover the second surface of the LED chip 10 and partially cover the first side of the LED chip 10.

[0074] In another alternative embodiment, the LED chip 10 has a second surface opposite to the first surface 101 and a first side surface surrounding the first surface 101. The step of bonding the LED chip 10 to the transient substrate 30 by the adhesive layer 40 includes: making the adhesive layer 40 completely cover the second surface of the LED chip 10, and fixing the LED chip 10 to the transient substrate 30 by the adhesive layer 40 on the second surface.

[0075] In the above embodiments, after the growth substrate 20 is peeled off, since the first surface 101 and the first side surface of the LED chip 10 are completely exposed, the subsequently formed support layer 50 can be connected to the first surface 101 and the first side surface. At the same time, the support layer 50 can completely cover the first side surface of the LED chip 10, thereby achieving a more stable connection with the LED chip 10.

[0076] In the above embodiments, adhesive material can be coated on the surface of the transient substrate 30 and bonded to the second surface of the LED chip 10. Then, the adhesive material is cured to form an adhesive layer 40 that connects the transient substrate 30 and the LED chip 10, so that the adhesive layer 40 completely covers the second surface of the LED chip 10.

[0077] It should be noted that in some other embodiments of this application, other bonding methods can also be used to transfer the LED chip 10 to the transient substrate 30, such as eutectic bonding, van der Waals force bonding, etc.

[0078] In some embodiments of this application, the transient substrate 30 includes any one of a silicon substrate, a silicon carbide substrate, and a gallium arsenide substrate. The transient substrates made of the above materials have lower hardness compared to substrates such as sapphire and lift-off substrates in the prior art. Using the above-mentioned optional substrate types can reduce the difficulty of etching to form the through-channel.

[0079] In some embodiments of this application, a laser lift-off process is used to peel off the growth substrate 20 so that the first surface 101 is exposed. The process conditions of the laser lift-off process can be reasonably set according to the type of growth substrate 20, which will not be described in detail in this application.

[0080] In some embodiments of this application, the adhesive layer 40 located between adjacent LED chips 10 on the transient substrate 30 is removed, such as... Figure 8 As shown. By removing the adhesive layer 40 between adjacent LED chips 10, the support layer 50 can be directly connected to the transient substrate 30 in the subsequent step of forming the support layer 50, thereby enabling the support layer 50 to be more firmly connected to the transient substrate 30.

[0081] After the step of transferring the LED chip 10 to the transient substrate 30, a support layer 50 for connecting the LED chip 10 is formed on the transient substrate 30, and as shown in the figure. Figure 9and Figure 10 As shown. The aforementioned support layer 50 is connected to the LED chip 10, while at least a portion of the first surface 101 of the LED chip 10 is exposed. The exposed first surface 101 serves as a force-bearing surface for subsequently applying force to the LED chip 10 to separate the LED chip 10 from the support layer 50.

[0082] Typically, the support layer 50 has little or no deformation capacity. This prevents the LED chip 10 from moving away from the support layer 50 due to pressure from the operating body, ensuring the support layer 50 can detach cleanly and easily from the LED chip 10 instead of continuing to follow it through deformation. In this embodiment, the support layer 50 can be made of a brittle material with a breaking stress lower than or far below the material's yield strength. Examples of materials for the support layer 50 include, but are not limited to, SiO2 (silicon oxide), graphite, and metals (including metals with high carbon content, such as cast iron).

[0083] The support layer 50 and the LED chip 10 can have different connection methods, and this application does not impose specific limitations. For example, the LED chip 10 has a first side surface surrounding the first surface 101. In the step of forming a support layer connecting the LED chip 10 on the transient substrate 30, the support layer 50 can connect only a portion of the first surface 101 of the LED chip 10, or only a portion of the first side surface of the LED chip 10, or simultaneously connect to a portion of the first surface 101 and at least a portion of the first side surface of the LED chip 10.

[0084] In some embodiments of this application, the step of forming a support layer 50 for connecting the LED chip 10 on the transient substrate 30 includes: forming a support preparation layer 510 for encapsulating the LED chip 10 on the transient substrate 30, such as... Figure 9 As shown; the support preparation layer 510 located on the first surface 101 is patterned so that at least part of the first surface 101 is exposed, and the remaining support preparation layer 510 constitutes the support layer 50, as shown. Figure 10 As shown. By first forming a support preparation layer 510 that encapsulates the LED chip 10, and then etching to expose the force-bearing surface of the LED chip 10, the formed support layer 50 can be stably connected to the transient substrate 30. The process is simple and easy to implement.

[0085] In the above embodiment, the step of patterning the support preparation layer 510 located on the first surface 101 may include: etching the support preparation layer 510 located on the first surface 101 so that the remaining support preparation layer 510 surrounds the edge of the first surface 101. By forming a support layer 50 surrounding and connected to the edge of the first surface 101 of the LED chip 10, not only can the support layer 50 be more firmly connected to the transient substrate 30, but also a larger exposed area can be provided in the first surface 101, thereby providing a larger force-bearing area. Consequently, the LED chip 10 can be transferred to the target substrate 60 by applying a smaller force in the subsequent process.

[0086] The remaining support preparation layer 510 surrounds the edge of the first surface 101. The exposed areas of the first surface 101 not covered by the support preparation layer 510 serve as force-bearing surfaces for subsequently applying force to the LED chip 10 to separate the LED chip 10 from the support layer 50. The shape of the exposed areas in the first surface 101 includes, but is not limited to, circles, ellipses, rhombuses, triangles, rectangles, etc. In addition, they can also be trapezoids, pentagons, and other regular or irregular shapes.

[0087] In the step of forming the support preparation layer 510 on the transient substrate 30, deposition processes such as PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), PECVD (Plasma Enhanced Chemical Vapor Deposition), and EV (vacuum evaporating) can be used.

[0088] For example, a support preparation layer 510 is formed on the transient substrate 30 using a PECVD process. Compared to other deposition processes in the prior art, the PECVD (plasma-enhanced chemical vapor deposition) process can effectively avoid the impact on device performance caused by the deposited material entering the epitaxial structure 110 of the LED chip 10.

[0089] In the above embodiments, the shape of the LED chip 10 can be defined so that the support preparation layer 510 deposited on the transient substrate 30 only covers the first surface 101 of the LED chip 10. For example, if the shape of the LED chip 10 is an inverted trapezoid, during the deposition process, the material of the support preparation layer 510 only falls on the first surface 101 of the LED chip 10 and does not contact the first side surface of the LED chip 10.

[0090] For example, the material forming the support preparation layer 510 includes any one or more of silicon oxide, silicon nitride, and silicon oxynitride. Using the above materials as the material for subsequently forming the support layer 50 not only enables the support layer 50 to be firmly connected to the transient substrate 30, but also has mature technology and low cost.

[0091] After the step of forming the support layer 50 connecting the LED chip 10 on the transient substrate 30, a through channel 310 is formed in the transient substrate 30, such as... Figure 11 and Figure 12 As shown.

[0092] A through-channel 310 is formed in the transient substrate 30. Undoubtedly, the through-channel 310 is a channel penetrating both sides of the transient substrate 30. Depending on the number of LED chips 10 to be transferred, there can be one or more through-channels 310. Multiple through-channels 310 can be arranged in an array in the transient substrate 30. However, those skilled in the art will understand that in other examples, the arrangement of the transient substrate 30 can also employ other implementation methods. Since the through-channel 310 is used to transfer the passing LED chips 10 to the target substrate, the arrangement of the through-channels 310 in the transient substrate 30 is related to the arrangement of the LED chips 10. When it is necessary to transfer a large number of LED chips 10 onto the target backplane (driving substrate), the arrangement of the through-channels 310 in the transient substrate 30 can refer to the arrangement of each chip receiving area on the target backplane. Furthermore, since the LED chips 10 are directly transferred from the growth substrate to the transient substrate, the arrangement of the through-channels 310 in the transient substrate 30 can also refer to the arrangement of the LED chips 10 on the growth substrate.

[0093] It should be noted that this application does not limit the shape of the through channel 310. For example, the cross-section of the through channel 310 can also be circular, elliptical, parallelogram, etc., as long as the through channel 310 can allow the LED chip 10 to pass through and be transferred to the target substrate.

[0094] In some embodiments of this application, the step of forming through channels 310 in the transient substrate 30 includes: patterning the transient substrate 30 to form a plurality of through channels 310 corresponding one-to-one with the LED chips 10 in the transient substrate 30, wherein, in a direction parallel to the transient substrate 30, the minimum cross-sectional dimension of each through channel 310 is larger than the maximum cross-sectional dimension of each LED chip 10, such as... Figure 11 As shown, the LED chip 10 separates from the support layer 50 under the action of an applied external force and is transferred to the target substrate 60 due to gravity. By forming the through channels 310 that correspond one-to-one with the LED chip 10, the LED chip 10 can be prevented from flipping during the fall, which greatly improves the transfer yield.

[0095] To further prevent the LED chip 10 from undergoing large positional shifts or even flipping during its passage through the through channel 310, the cross-sectional size of the through channel 310 can be made relatively small. For example, in some examples of this embodiment, the cross-sectional size of the through channel 310 is only slightly larger than the cross-sectional size of the LED chip 10.

[0096] In some embodiments of this application, the depth of the through-channel is H1, and the height of the LED chip in the depth direction of the through-channel is H2, where H1 > H2. During the chip transfer process at a predetermined position on the target substrate, since LED chips may already be provided at other positions on the target substrate corresponding to different through-channels, by ensuring that the depth of the through-channel and the height of the LED chip satisfy the above relationship, it is possible to avoid affecting chips at other positions when repairing chips at the predetermined position.

[0097] When the LED chip 10 is transferred to the transient substrate 30 using the adhesive layer 40, after the step of forming the through-channel 310 described above, the adhesive layer 40 needs to be removed to allow the LED chip 10 to communicate with the through-channel 310, such as... Figure 12 As shown.

[0098] After forming the support layer 50 having the through-channel 310 and connecting the LED chips 10, the LED chips 10 are disposed on one side of the target substrate 60 through the support layer 50, and a force is applied to the first surface 101 to transfer each LED chip 10 to the target substrate 60 through the through-channel 310, such as... Figure 13 and Figure 14 As shown. For example, a force can be applied to the first surface 101 of the LED chip 10 by means of a pin.

[0099] It is understood that forces can be applied simultaneously to the first surface 101 of different LED chips 10 to transfer multiple LED chips 10 onto the target substrate 60, for example, multiple ejector pins can simultaneously eject different LED chips 10, thereby improving the transfer efficiency of the LED chips 10.

[0100] Typically, after a large number of LED chips 10 are transferred to the target substrate 60, there may be gaps in some target positions on the target substrate 60, meaning that the LED chips 10 corresponding to the target positions have not been transferred. After bonding the LED chips 10, there may also be some LED chips with poor bonding. In this case, after bonding the LED chips 10 to the target substrate 60, the defective LED chips on the target substrate 60 can be identified by detection, and then the defective LED chips can be removed from the target substrate 60. Chip repair can then be performed at the gaps or at the locations where the defective LED chips have been removed.

[0101] To achieve chip repair at the target location, in some embodiments of this application, the step of applying a force to the first surface 101 to transfer each LED chip 10 through the through-channel 310 to the target substrate 60 further includes: providing the target substrate 60, one side surface of the target substrate 60 having a target region 610; and disposing of a transient substrate 30 on the target substrate 60 such that the LED chip 10 is located on the side of the transient substrate 30 away from the target substrate 60 and corresponds to the target region 610, such as... Figure 15 As shown; a force is applied to the first surface 101 to transfer the LED chip 10 through the through-channel 310 to the target region 610, as shown. Figure 16 As shown. When the target area 610 is an empty space or a location where a defective LED chip has been removed, the above steps can be used to repair the chip in the target area 610.

[0102] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A chip transfer method, characterized in that, Includes the following steps: A growth substrate with multiple LED chips formed on its surface is provided; The LED chip is transferred to a transient substrate, and the growth substrate is peeled off, with the side of the LED chip away from the transient substrate having an exposed first surface; A support layer for connecting the LED chip is formed on the transient substrate. The LED chip has a first side surface surrounding the first surface. The support layer connects a portion of the first surface and / or at least a portion of the first side surface, so that at least a portion of the first surface is exposed. A through-channel is formed in the transient substrate to form a plurality of through-channels corresponding one-to-one with the LED chips. In the direction parallel to the transient substrate, the minimum cross-sectional dimension of each through-channel is greater than the maximum cross-sectional dimension of each LED chip. A force is applied to the first surface to transfer each of the LED chips to the target substrate through the through-channel.

2. The chip transfer method as described in claim 1, characterized in that, Each of the LED chips includes an epitaxial structure, a first electrode, and a second electrode, wherein the first electrode and the second electrode are located on the side of the epitaxial structure away from the growth substrate; After the step of transferring the LED chip to the transient substrate, the epitaxial structure is located on the side of the first electrode and the second electrode away from the transient substrate, and the epitaxial structure has the first surface.

3. The chip transfer method as described in claim 1, characterized in that, The step of transferring the LED chip to the transient substrate includes: The LED chip is bonded to the transient substrate using an adhesive layer, such that the growth substrate is located on the side of the LED chip away from the transient substrate; The growth substrate is peeled off to expose the first surface.

4. The chip transfer method as described in claim 3, characterized in that, Prior to the step of forming the support layer on the first surface of the connection portion on the transient substrate, the chip transfer method further includes the following steps: Remove the adhesive layer located between adjacent LED chips on the transient substrate.

5. The chip transfer method according to any one of claims 1 to 4, characterized in that, The LED chip has a first side surface surrounding the first surface. In the step of forming the support layer connecting the LED chip on the transient substrate, the support layer connects a portion of the first surface and / or at least a portion of the first side surface.

6. The chip transfer method as described in claim 5, characterized in that, The step of forming the support layer connecting the LED chip on the transient substrate includes: A support preparation layer encapsulating the LED chip is formed on the transient substrate; The support preparation layer located on the first surface is patterned so that at least part of the first surface is exposed, and the remaining support preparation layer constitutes the support layer.

7. The chip transfer method according to any one of claims 1 to 4, characterized in that, The step of forming the through channel in the transient substrate includes: The transient substrate is patterned to form a plurality of through channels corresponding one-to-one with the LED chips in the transient substrate. In a direction parallel to the transient substrate, the minimum cross-sectional size of each through channel is greater than the maximum cross-sectional size of each LED chip.

8. The chip transfer method according to any one of claims 1 to 4, characterized in that, The transient substrate includes any one of a silicon substrate, a silicon carbide substrate, and a gallium arsenide substrate.

9. The chip transfer method according to any one of claims 1 to 4, characterized in that, The depth of the through channel is H1, and the height of the LED chip is H2 in the depth direction of the through channel, where H1 > H2.

10. The chip transfer method according to any one of claims 1 to 4, characterized in that, The step of applying a force to the first surface to transfer each of the LED chips through the through-channel to the target substrate includes: A target substrate is provided, wherein one side surface of the target substrate has a target region; The transient substrate is disposed on the target substrate such that the LED chip is located on the side of the transient substrate away from the target substrate and corresponds to the target area; A force is applied to the first surface to transfer the LED chip to the target area through the through-channel.

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