Chip transfer method, substrate and display panel

Abstract

The present application relates to a chip transfer method, a substrate and a display panel. The chip transfer method comprises providing a substrate, the substrate having a light emitting chip grown on one side of the substrate, the substrate being provided with a thermochromic layer, the thermochromic layer being configured to reduce the transmittance of laser light when the interface temperature at the growth interface between the substrate and any light emitting chip is higher than a preset temperature; irradiating the thermochromic layer with laser light, the thermochromic layer reducing the transmittance of laser light when the interface temperature at the growth interface between the substrate and any light emitting chip is higher than the preset temperature; and the thermochromic layer maintaining the transmittance of laser light when the interface temperature at the growth interface between the substrate and any light emitting chip is lower than the preset temperature, so as to separate the light emitting chip and transfer the light emitting chip to a target substrate. The chip transfer method is advantageous in reducing damage of the light emitting chip caused by high heat generated by high-intensity irradiation of laser light in some implementation processes.

Description

Technical Field

[0001] This invention relates to the field of light-emitting chip manufacturing, and more particularly to a chip transfer method, a substrate, and a display panel. Background Technology

[0002] Micro-LED (Micro Light-Emitting Diode) display devices have advantages such as fast response speed, low power consumption and excellent color display effect. However, there are still many problems in the manufacturing process. For example, a large number of defective Micro-LED chips may be generated during the laser stripping process, which will increase the manufacturing cost of the display device and degrade the display effect.

[0003] The principle of laser lift-off is that laser heating causes the gallium nitride at the interface between the chip and the growth substrate on the wafer to absorb photon energy and generate heat, which causes the temperature to rise. When the decomposition temperature is reached (890℃ at normal pressure), it decomposes into metallic gallium and nitrogen gas. However, the laser energy may be abnormally controlled or fluctuate, resulting in excessively high interface temperature, which may cause the Micro-LED chip to crack due to thermal effects or the epitaxial layer of the chip to be decomposed.

[0004] Therefore, how to protect the light-emitting chip during the laser stripping process is an urgent problem to be solved. Summary of the Invention

[0005] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a chip transfer method, a substrate and a display panel, which aims to solve the problem that when using laser to peel off chips, the laser energy may damage the chips and affect the product yield.

[0006] A chip transfer method, comprising:

[0007] A substrate is provided, on one side of which a light-emitting chip is grown. The substrate is provided with a thermochromic layer, which is used to reduce the transmittance of laser when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than a preset temperature.

[0008] The thermochromic layer is irradiated with a laser, wherein when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than the preset temperature, the thermochromic layer reduces the transmittance of the laser; when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is lower than the preset temperature, the thermochromic layer maintains the transmittance of the laser to facilitate the peeling off of the light-emitting chips.

[0009] The light-emitting chip is transferred to the target substrate.

[0010] The aforementioned chip transfer method utilizes a substrate with a thermochromic layer and a chip for laser peeling. When the laser needs to peel off the light-emitting chip, it irradiates the thermochromic layer. Therefore, when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than the preset temperature, the thermochromic layer reduces the laser transmittance, thereby reducing the intensity of the laser actually irradiating the growth interface between the light-emitting chip and the substrate. This suppresses the heat generated by the laser between the light-emitting chip and the substrate, which in some implementations helps to reduce damage to the light-emitting chip caused by high heat generated by high-intensity laser irradiation.

[0011] Optionally, before irradiating the thermochromic layer with a laser, the method further includes:

[0012] The temporary storage substrate is bonded to the light-emitting chip on the substrate;

[0013] After irradiating the thermochromic layer with a laser, the method further includes:

[0014] The substrate and the light-emitting chip are separated, leaving the light-emitting chip on the temporary substrate.

[0015] Optionally, transferring the light-emitting chip to the target substrate includes:

[0016] The light-emitting chip is transferred from the temporary substrate to the target substrate using a transfer device.

[0017] Optionally, providing a substrate includes:

[0018] The thermochromic layer is formed on the surface of the substrate on the side where the light-emitting chip is not grown.

[0019] Optionally, forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown includes at least one of the following:

[0020] A thermochromic material is deposited on the surface of the side of the substrate where the light-emitting chip is not grown by means of a sol-gel method.

[0021] A thermochromic material is deposited on the side of the substrate where the light-emitting chip is not grown by magnetron sputtering.

[0022] Optionally, forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown includes:

[0023] The target thermochromic material is determined based on the thickness of the substrate, its heat dissipation capacity, and the damage temperature of the light-emitting chip, so that the preset temperature is lower than the damage temperature of the light-emitting chip.

[0024] The thermochromic layer is formed using the target thermochromic material.

[0025] Optionally, before forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown, the method further includes:

[0026] The target thickness of the substrate is determined based on the heat dissipation capacity of the substrate, the abrupt change temperature of the thermochromic layer, and the damage temperature of the light-emitting chip; so that the preset temperature is lower than the damage temperature of the light-emitting chip; and the thermochromic layer reduces the transmittance of laser light when its own temperature is higher than the abrupt change temperature.

[0027] Before forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown, the method further includes:

[0028] A substrate with a thickness equal to the target thickness is provided.

[0029] Based on the same inventive concept, this application also provides a substrate on one side of which a light-emitting chip can be grown. The substrate is provided with a thermochromic layer, which is used to reduce the transmittance of laser when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than a preset temperature, and to maintain the transmittance of laser when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is lower than the preset temperature.

[0030] When the chip grown on the aforementioned substrate is peeled off by laser, the laser can irradiate the thermochromic layer. Therefore, when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than the preset temperature, the thermochromic layer reduces the laser transmittance, which reduces the intensity of the laser actually irradiating the growth interface between the light-emitting chip and the substrate. This suppresses the heat generated by the laser between the light-emitting chip and the substrate. It is evident that the aforementioned substrate helps to reduce the damage to the light-emitting chip caused by high heat generated by high-intensity laser irradiation.

[0031] Optionally, the thermochromic layer is disposed on the surface of the substrate on the side where the light-emitting chip is not grown.

[0032] Based on the same inventive concept, this application also provides a display panel, the display panel including a light-emitting chip and a circuit substrate, wherein the light-emitting chip is transferred to the die-bonding region of the circuit substrate by the chip transfer method described above.

[0033] The light-emitting chips of the aforementioned display panel are transferred using the chip transfer method described above, which helps to reduce damage to the light-emitting chips during the transfer process, resulting in a high-quality display panel and a high yield of the transferred light-emitting chips. Attached Figure Description

[0034] Figure 1This is a schematic diagram of a basic process of the chip transfer method provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of the substrate provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of a thermochromic layer irradiated by laser according to an embodiment of the present invention;

[0037] Figure 4 A schematic diagram showing a local area with a temperature higher than a preset temperature, provided in an embodiment of the present invention;

[0038] Figure 5 This is a detailed flowchart illustrating the chip transfer method provided in an embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram of the temporary storage substrate and the substrate being bonded together in an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of a substrate stripping process provided in an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of another structure of the substrate provided in an embodiment of the present invention;

[0042] Explanation of reference numerals in the attached figures:

[0043] 1-Substrate; 11-Thermochromic layer; 2-Light-emitting chip; 3-Temporary storage substrate; 31-Die bonding area. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] In related technologies, when using lasers to peel off chips, the laser energy may damage the chips, affecting product yield.

[0047] 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.

[0048] Example:

[0049] This embodiment provides a chip transfer method; please refer to [link to relevant documentation]. Figure 1 The chip transfer method includes:

[0050] S101, Provide a substrate;

[0051] It should be noted that, such as Figure 2 A chip 2 is grown on one side of a substrate 1. A thermochromic layer 11 is disposed on the substrate 1. The thermochromic layer 11 is used to reduce the transmittance of laser light when the interface temperature at the growth interface between the substrate and any light-emitting chip is higher than a preset temperature. It is understood that in this embodiment, the thermochromic layer 11 is disposed at least in the area corresponding to the chip 2.

[0052] The substrate can be a growth substrate for growing light-emitting chips, and its material can be a semiconductor material capable of growing epitaxial layers of light-emitting chips, such as including but not limited to sapphire, silicon carbide, silicon, gallium arsenide, or other semiconductor materials, without limitation.

[0053] The light-emitting chips that can be grown on the substrate include, but are not limited to, LED (Light-Emitting Diode) chips or other light-emitting chips. The LED chips can be Micro-LED chips or Mini-LED (Mini Light-Emitting Diode) chips, etc.

[0054] S102. Using laser irradiation of the thermochromic layer;

[0055] like Figure 3 As shown, since the light-emitting chip 2 is disposed on one side of the substrate 1, when the laser irradiates the thermochromic layer 11, the light passes through the thermochromic layer 11 and the substrate 1 to irradiate the light-emitting chip 2. It is understood that during normal peeling, the transmittance of the thermochromic layer ensures that the laser can decompose the bonding material at the interface between the light-emitting chip and the substrate. This laser includes lasers capable of decomposing the bonding material at the interface between the light-emitting chip and the substrate; that is, in practical applications, the laser (or the power of the laser) is selected according to the bonding material between the light-emitting chip and the substrate. In some examples, a layer of gallium nitride (GaN) is included between the light-emitting chip and the substrate. The GaN is heated by the laser, and the GaN between the light-emitting chip and the substrate absorbs photon energy to generate heat. When the decomposition temperature of gallium nitride (890℃ at ambient pressure) is reached, the gallium nitride decomposes into metallic gallium (Ga) and nitrogen gas (N2). When the bonding material between the light-emitting chip and the substrate is completely decomposed, the light-emitting chip can detach from the substrate, achieving peeling of the light-emitting chip.

[0056] S103, Transfer the light-emitting chip to the target substrate;

[0057] The target substrate includes, but is not limited to, circuit substrates, such as driver backplanes.

[0058] In this embodiment, the light-emitting chip can be peeled off from the substrate and transferred to the target substrate in any manner. For example, the light-emitting chips can be picked up one by one or simultaneously from the substrate and placed on the target substrate; or the target substrate can be directly bonded to the substrate so that the target substrate directly contacts and bonds to the light-emitting chip on the substrate. The target substrate can be bonded to the light-emitting chip by means including but not limited to adhesive bonding and welding, thereby fixing the light-emitting chip to the target substrate and detaching the light-emitting chip from the substrate.

[0059] During the peeling process of the light-emitting chip, when using a laser to peel the chip, the interface temperature at the growth interface between the light-emitting chip and the substrate can be controlled to reach the required decomposition temperature by controlling the laser power intensity. This decomposes the bonding material at the growth interface, and it is understood that this decomposition temperature will not damage the light-emitting chip. However, laser control is not absolutely stable. Due to laser energy fluctuations or abnormalities in related control, the laser may output higher power, leading to excessively high temperatures. In the chip transfer method of this embodiment, laser peeling is performed on the substrate including a thermochromic layer and the light-emitting chip during the light-emitting chip transfer process. When the interface temperature at the growth interface between the substrate and any light-emitting chip is higher than a preset temperature, the thermochromic layer changes, reducing the laser transmittance. This reduces the intensity of the laser actually irradiating the growth interface between the light-emitting chip and the substrate, thereby suppressing the heat generated by the laser at the growth interface between the light-emitting chip and the substrate. It can be seen that the chip transfer method of this embodiment can control the maximum temperature that the light-emitting chip may experience during the peeling process to a certain extent. Therefore, in some implementations, the above-mentioned chip transfer method is beneficial in reducing damage to the light-emitting chip caused by high heat generated by high-intensity laser irradiation. For example, when peeling off the light-emitting chip, if the energy of the laser fluctuates and the intensity is too high, causing the interface temperature at the growth interface between the substrate and any light-emitting chip to be higher than the preset temperature, it can suppress the further rise of the interface temperature, and may even cause the interface temperature to drop, thus preventing the light-emitting chip from being in or for a long time in a condition higher than the preset temperature.

[0060] Furthermore, when the interface temperature of the thermochromic layer at the growth interface between the substrate and any light-emitting chip is higher than a preset temperature, the laser transmittance decreases. In some implementations, see [link to relevant documentation]. Figure 4 It is possible that only localized areas experienced excessively high temperatures (e.g.) Figure 4 If region A in the diagram is selected, then only a localized area at the growth interface between the substrate and the light-emitting chip has a temperature higher than the preset temperature. Therefore, the thermochromic layer corresponding to this portion (e.g., region A) will be affected. Figure 4The B region of the thermochromic layer changes, but the removal of the light-emitting chip in the remaining regions remains unaffected.

[0061] In this embodiment, when the interface temperature at the growth interface between the substrate and any light-emitting chip is lower than a preset temperature, the thermochromic layer maintains the laser transmittance. It should be noted that in this embodiment, the thermochromic layer maintaining the laser transmittance refers to maintaining the laser transmittance below the preset temperature. That is, when the interface temperature at the growth interface between the substrate and any light-emitting chip is high (above the preset temperature), the thermochromic layer will reduce the laser transmittance; however, when the temperature decreases (below the preset temperature), the laser transmittance will increase again and remain below the preset temperature. Therefore, by using a thermochromic layer, the substrate temperature during the peeling of the light-emitting chip can be controlled within a certain range. When the temperature is too high, the thermochromic layer reduces the light transmittance, inhibiting further temperature increases, and can restore its light transmittance after the temperature decreases, ensuring that the bonding material at the growth interface between the light-emitting chip and the substrate continues to decompose, allowing the light-emitting chip to be peeled off.

[0062] In some embodiments, the thermochromic layer can be a vanadium oxide, such as, but not limited to, at least one of the following substances: vanadium monoxide (VO), vanadium trioxide (V₂O₃), vanadium dioxide (VO₂), vanadium trioxide (V₃O₅), and vanadium pentoxide (V₂O₅). These vanadium oxides, when the temperature reaches their specific crystal structure abrupt change point, can undergo a transition from a low-temperature monoclinic phase to a high-temperature metallic tetragonal rutile phase. In the high-temperature metallic crystal structure, the tetravalent vanadium ion V₄⁺ occupies the vertices and center of the unit cell, and is also the oxygen ion O₂. 2- When the crystal structure at the center of the octahedron undergoes abrupt changes due to temperature, the crystal axis length changes, and the tetravalent vanadium ion V 4+ The vanadium oxide will leave its original position, with the β angle increasing by 33° (taking vanadium dioxide as an example), forming a special structure characteristic of low-temperature semiconductors. When vanadium oxide undergoes a abrupt change in crystal structure, not only does the energy change, but the volume of the unit cell also changes. Since this change in unit cell also leads to a change in optical transmittance, it can suppress laser irradiation. The abrupt change in the crystal structure of vanadium oxide is reversible; when the temperature decreases below its abrupt change point, the crystal structure recovers, and the light transmittance also recovers. Vanadium oxide can serve as a highly sensitive thermochromic layer, achieving excellent control over the temperature of the light-emitting chip stripping process and improving the stability of the light-emitting chip transfer.

[0063] Understandably, different materials used in the thermochromic layer may correspond to different specific temperatures. For example, the crystal structure transition temperature of vanadium monoxide is 110 Kelvin, vanadium trioxide is 155 Kelvin, vanadium dioxide is 340 Kelvin, vanadium trioxide is 420 Kelvin, and vanadium pentoxide is 531 Kelvin. By selecting different materials as the thermochromic layer, different temperature control requirements can be achieved.

[0064] It is understandable that, in addition to the thermochromic materials mentioned above, there are other thermochromic materials, and the thermochromic layer can also use any other thermochromic material that can reduce laser transmittance at a specific temperature higher than room temperature.

[0065] Understandably, the selection of the preset temperature is based on the actual situation. This preset temperature is usually higher than the temperature required to peel off the light-emitting chip, but lower than the damage temperature that would harm the chip.

[0066] In practical applications, the laser primarily generates heat at the bonding material between the light-emitting chip and the substrate. In some embodiments, the thermochromic layer does not directly contact the growth interface between the substrate and any of the light-emitting chips. To ensure protection of the light-emitting chips, the abrupt change temperature of the thermochromic layer is chosen to be lower than a preset temperature. That is, the selected thermochromic layer changes color when its own temperature is lower than the preset temperature, reducing light transmittance. For example, in some examples, the thermochromic layer is located on the other side of the substrate, and the distance between the thermochromic layer and the growth interface between the substrate and the light-emitting chip is relatively large. Heat must be conducted through the entire thickness of the substrate to the thermochromic layer. During this process, a large amount of heat is dissipated, and the actual temperature sensed by the thermochromic layer is much lower than the actual temperature of the growth interface. Therefore, choosing a material with an abrupt change temperature much lower than the preset temperature to form the thermochromic layer ensures that the light-emitting chip can be easily peeled off without causing the actual temperature of the light-emitting chip to become too high. It is understandable that when the thermochromic layer reaches its abrupt change temperature, if the actual temperature of the light-emitting chip at this time is not higher than the temperature at which it would be damaged, then the light-emitting chip can be well protected. In other words, the temperature can be controlled within a range that allows the light-emitting chip to be peeled off without damaging it. In some examples, when the thermochromic layer reaches its abrupt change temperature, the actual temperature of the light-emitting chip is slightly lower than the temperature at which it would be damaged.

[0067] In some embodiments, before irradiating the thermochromic layer with a laser, the following steps are also included:

[0068] S104. Bond the temporary storage substrate to the light-emitting chip on the substrate;

[0069] After irradiating the thermochromic layer with a laser, the process also includes:

[0070] S105, peel off the substrate and the light-emitting chip, leaving the light-emitting chip on the temporary substrate.

[0071] To better understand, the following example, in conjunction with the accompanying drawings, provides a more detailed explanation. In this example, the temporary storage substrate has an adhesive layer for bonding to the light-emitting chip. See also... Figure 5 The chip transfer method in this example specifically includes:

[0072] S101, Provide a substrate;

[0073] S1041, Temporary storage substrate and substrate are bonded together facing each other;

[0074] like Figure 6 The temporary storage substrate 3 has an adhesive layer 31 on one side facing the side of the substrate 1 where the light-emitting chip 2 is grown, and the two are brought close together until they come into contact to be bonded. It is understood that in other examples, the bonding method may include soldering.

[0075] S102. Using laser irradiation of the thermochromic layer;

[0076] To ensure better removal of the light-emitting chip and to protect it, the laser beam is directed perpendicularly to the substrate. The laser irradiates the thermochromic layer until the light-emitting chip can be peeled off from the substrate.

[0077] S105: Separate the substrate from the light-emitting chip, leaving the light-emitting chip on the temporary substrate;

[0078] like Figure 7 The substrate 1 can be removed directly by adsorption, clamping or other means. Due to the effect of the laser, the bonding material at the growth interface between the light-emitting chip 2 and the substrate 1 is decomposed. The light-emitting chip 2 and the substrate 1 no longer have bonding force or the bonding force is very weak. The bonding force between the light-emitting chip 2 and the temporary substrate 3 is stronger. The light-emitting chip 2 is left on the temporary substrate 3.

[0079] S103, Transfer the light-emitting chip to the target substrate.

[0080] In some embodiments, transferring the light-emitting chip to the target substrate includes: transferring the light-emitting chip from a temporary storage substrate to the target substrate using a transfer device. The transfer device includes, but is not limited to, various transfer heads, transfer substrates, and other devices capable of picking up and transferring the light-emitting chip from the temporary storage substrate to the target substrate.

[0081] In another example, the light-emitting chip is directly transferred to a circuit board substrate. The circuit board substrate has a die-bonding region for bonding to the light-emitting chip and is connected to a driving circuit. The light-emitting chip is first bonded to the die-bonding region and connected to the driving circuit, which controls the driving of the light-emitting chip. The process of transferring the light-emitting chip to the circuit board substrate can be essentially the same as transferring it to a temporary storage substrate. However, in this process, the die-bonding region of the circuit board substrate is aligned with the light-emitting chip on the substrate. Accurate alignment can be achieved using techniques such as CCD (Charge Coupled Device) alignment technology. Finally, the die-bonding region of the circuit board contacts the light-emitting chip on the substrate. The die-bonding region of the circuit board substrate has solder. By heating, the solder melts, and the light-emitting chip and the circuit board are bonded together.

[0082] The thermochromic layer can be pre-formed with the substrate; please refer to [link / reference]. Figure 8 In some examples, the thermochromic layer 11 may also be located inside the substrate 1, rather than on the surface of the substrate 1. That is, in some examples, the substrate provided in step S101 above already has the thermochromic layer before the growth of the light-emitting chip. In some embodiments, the light-emitting chip is grown on the substrate first, and then the thermochromic layer is formed. That is, as long as the light-emitting chip is grown on the substrate and the thermochromic layer is provided before the light-emitting chip is peeled off, it is sufficient. In other embodiments, the thermochromic layer can be fabricated before or after the growth of the light-emitting chip, that is, step S101 above may also include:

[0083] S1011. A thermochromic layer is formed on the surface of the side of the substrate where no light-emitting chip is grown;

[0084] In some embodiments, a thermochromic layer is formed on the surface of the substrate on the side where no light-emitting chip is grown, including but not limited to at least one of the following:

[0085] Thermochromic materials are deposited on the surface of the substrate on the side where no light-emitting chip is grown using the sol-gel method.

[0086] Thermochromic material is deposited on the surface of the substrate on the side where no light-emitting chip is grown by magnetron sputtering.

[0087] If light-emitting chips can be grown on both sides of the substrate, a thermochromic layer can be formed on either side of the substrate. During subsequent growth of the light-emitting chip, the chip is grown on the side without the thermochromic layer. If a light-emitting chip has already been grown on the substrate, a thermochromic layer is formed on the side of the substrate where no light-emitting chip has grown.

[0088] Please refer to the following two examples, which illustrate two methods for setting the temperature control range of the substrate, based on the actual temperature control requirements. It is understood that the methods in the following examples can be used independently or in combination.

[0089] Example 1: By selecting a target thermochromic material, temperature selection is achieved; that is, in this example, forming a thermochromic layer on the surface of the substrate where no light-emitting chip is grown includes:

[0090] Based on the substrate thickness, heat dissipation capacity, and damage temperature of the light-emitting chip, a target thermochromic material is selected to ensure that the preset temperature is lower than the damage temperature of the light-emitting chip.

[0091] A thermochromic layer is formed using the target thermochromic material.

[0092] Understandably, all other things being equal, the different abrupt change temperatures of the thermochromic layer determine the maximum temperature the light-emitting chip can withstand. The lower the abrupt change temperature of the thermochromic layer, the lower the maximum temperature the light-emitting chip can withstand, and vice versa. This example demonstrates how, by appropriately selecting the target thermochromic material, the maximum temperature the light-emitting chip can withstand does not exceed its damage temperature.

[0093] Example 2: Temperature selection is achieved by setting the substrate thickness; that is, in this example, before the thermochromic layer is formed on the surface of the substrate where the light-emitting chip is not grown, the following steps are also included:

[0094] Based on the heat dissipation capacity of the substrate, the abrupt change temperature of the thermochromic material, and the damage temperature of the light-emitting chip, the target thickness of the substrate to be used is determined so that the preset temperature is lower than the damage temperature of the light-emitting chip; the thermochromic layer reduces the transmittance of laser when its own temperature is higher than the abrupt change temperature.

[0095] A thermochromic layer is formed on the surface of the side of the substrate where no light-emitting chip is grown, and the method further includes:

[0096] Provide a substrate with a thickness of the target thickness.

[0097] As an example of temperature control, the bonding material at the growth interface between the light-emitting chip and the substrate is gallium nitride (GaN), which serves as a buffer layer and decomposes at 890°C. In this example, the thermochromic layer can be made of vanadium dioxide (vanadium dioxide). Vanadium dioxide has a sudden temperature change of 340K (i.e., 66.85°C; for ease of comparison, this example uses degrees Celsius). Vanadium dioxide can be deposited on the substrate as a thermochromic layer using methods such as sol-gel deposition or magnetron sputtering. Since the light-emitting chip is in direct contact with the GaN buffer layer, the highest temperature the chip may experience is approximately equal to the temperature at which GaN decomposes. In this example, the highest possible temperature the chip may experience can be controlled to around 900°C, i.e., a preset temperature of 900°C. By controlling the substrate thickness, when the gallium nitride (GaN) temperature exceeds 900°C, the heat transferred from the substrate to the vanadium dioxide (vanadium dioxide) film raises the film's temperature to 66.85°C. This causes a crystal structure transformation in the vanadium dioxide, reducing its laser transmittance and blocking further laser irradiation. This prevents the GaN temperature from remaining above 900°C for an extended period. Conversely, when the GaN temperature drops below 900°C, the vanadium dioxide film cools accordingly to below 66.85°C, restoring its laser transmittance and maintaining it below this level, allowing the laser to continue irradiating the GaN normally. Ideally, during this process, the GaN temperature remains within the range of approximately 890°C to 900°C, ensuring proper peeling and preventing excessive heat exposure to the LED chip.

[0098] In this example, the thermochromic layer is formed on the surface of the substrate where the light-emitting chip is not located. The heat generated by the laser must travel across the entire thickness of the substrate before reaching the thermochromic layer. Therefore, with the actual temperature of the light-emitting chip remaining constant, a thicker substrate results in a lower temperature for the thermochromic layer, and vice versa. Thus, for the same type of thermochromic layer, when it reaches its abrupt temperature change, a thicker substrate leads to a higher actual temperature for the light-emitting chip, while a thinner substrate leads to a lower actual temperature. By controlling the thickness of the substrate, the actual temperature of the light-emitting chip when the thermochromic layer reaches a specific temperature is controlled.

[0099] Providing a substrate with a target thickness includes directly providing a substrate with a thickness equal to the target thickness; or performing processes such as thickening or thinning on a substrate with a thickness not equal to the target thickness to make its thickness equal to the target thickness. It is understood that the substrate thickening or thinning processes can be performed at any time before laser irradiation is applied to remove the light-emitting chip.

[0100] In other examples, temperature control can also be achieved by selecting other variables such as the substrate material. For instance, different materials can be used to control temperature by utilizing their varying heat dissipation capabilities. For substrates with weak heat dissipation capabilities, the temperature sensed by the thermochromic layer is closer to the actual temperature of the light-emitting chip. Conversely, using a substrate with stronger heat dissipation capabilities results in a temperature sensed by the thermochromic layer that is lower than the actual temperature of the light-emitting chip.

[0101] Another optional embodiment of the present invention:

[0102] This embodiment provides a substrate on one side of which a light-emitting chip can be grown. The substrate is provided with a thermochromic layer, which is used to reduce the transmittance of laser when the interface temperature at the growth interface between the substrate and any light-emitting chip is higher than a preset temperature, and to maintain the transmittance of laser when the interface temperature at the growth interface between the substrate and any light-emitting chip is lower than the preset temperature.

[0103] In some embodiments, the thermochromic layer is disposed on the surface of the substrate on the side where no light-emitting chip is grown. In other embodiments, the thermochromic layer may also be disposed inside the substrate.

[0104] For example, at least one side of the substrate is provided with a bonding material capable of growing a light-emitting chip, including but not limited to materials such as gallium nitride. In these examples, gallium nitride can serve as a buffer layer, enabling better lattice matching between the light-emitting chip and the substrate.

[0105] In some examples, the thermochromic layer may not cover all areas of the substrate, but it must at least be present in the area corresponding to the growth of the light-emitting chip. To remove the light-emitting chip, a laser is used to irradiate the thermochromic layer, passing through both the thermochromic layer and the substrate to reach the growth interface between the light-emitting chip and the substrate. Of course, in some examples, to facilitate the fabrication of the thermochromic layer or the growth of the light-emitting chip, the thermochromic layer completely covers the substrate, and there is no need to consider whether the areas where the thermochromic layer and the light-emitting chip are aligned when forming the thermochromic layer or growing the light-emitting chip.

[0106] In this embodiment, the light-emitting chip grown on the substrate can be peeled off by irradiating a thermochromic layer with a laser. When the interface temperature at the growth interface between the substrate and any light-emitting chip is higher than a preset temperature, the thermochromic layer reduces the laser transmittance, thereby reducing the intensity of the laser reaching the growth interface between the substrate and the light-emitting chip. This suppresses the heat generated by the laser at the growth interface between the light-emitting chip and the substrate. Therefore, the substrate in this embodiment can control the maximum temperature of the light-emitting chip during laser peeling to a certain extent. Thus, in some implementations, the substrate helps reduce damage to the light-emitting chip caused by high heat generated by high-intensity laser irradiation. For example, when peeling off the light-emitting chip, if the laser energy fluctuates, causing the interface temperature at the growth interface between the substrate and any light-emitting chip to exceed the preset temperature, further increases in the interface temperature can be suppressed, and the interface temperature may even decrease, preventing the light-emitting chip from being at or for an extended period at a high temperature.

[0107] The specific process of transferring the light-emitting chip using this substrate can be referred to the chip transfer method provided in the above embodiments; the selection of materials and fabrication of the substrate have also been described in the chip transfer method, and will not be repeated here. The substrate structure in some examples can also be found in the accompanying drawings provided in the above embodiments.

[0108] This embodiment also provides a display panel, which includes a light-emitting chip and a circuit substrate. The light-emitting chip is transferred to the die-bonding area of ​​the circuit substrate by the chip transfer method exemplified in the above embodiment.

[0109] For example, the above chip transfer method can directly transfer the light-emitting chip on the substrate to the circuit substrate. Alternatively, it can be transferred to a temporary storage substrate first, and then the light-emitting chip is transferred from the temporary storage substrate to the die-bonding area of ​​the circuit substrate. The light-emitting chip on the temporary storage substrate is picked up by a device including but not limited to a transfer head and a transfer substrate, and then the light-emitting chip is transferred to the circuit substrate by the transfer head, transfer substrate, or other such device.

[0110] The light-emitting chips of the above-described display panel are transferred using the chip transfer method exemplified in the above embodiments, which helps to reduce damage to the light-emitting chips during the peeling process from the substrate. Therefore, the display panel of this embodiment has better quality and a higher yield of the transferred light-emitting chips.

[0111] It should be understood that the application of the present invention 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, include: A substrate is provided, on one side of which a light-emitting chip is grown. The substrate is provided with a thermochromic layer, which is formed on the surface of the side of the substrate where the light-emitting chip is not grown. The thermochromic layer is used to reduce the transmittance of laser when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than a preset temperature. The thermochromic layer is irradiated with a laser, wherein when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than the preset temperature, the thermochromic layer reduces the transmittance of the laser; when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is lower than the preset temperature, the thermochromic layer maintains the transmittance of the laser to facilitate the peeling off of the light-emitting chips. The light-emitting chip is transferred to the target substrate.

2. The chip transfer method as described in claim 1, characterized in that, Before irradiating the thermochromic layer with a laser, the method further includes: The temporary storage substrate is bonded to the light-emitting chip on the substrate; After irradiating the thermochromic layer with a laser, the method further includes: The substrate and the light-emitting chip are separated, leaving the light-emitting chip on the temporary substrate.

3. The chip transfer method as described in claim 2, characterized in that, The process of transferring the light-emitting chip to the target substrate includes: The light-emitting chip is transferred from the temporary substrate to the target substrate using a transfer device.

4. The chip transfer method as described in claim 1, characterized in that, The thermochromic layer formed on the surface of the substrate on the side where the light-emitting chip is not grown includes at least one of the following: A thermochromic material is deposited on the surface of the side of the substrate where the light-emitting chip is not grown by means of a sol-gel method. A thermochromic material is deposited on the side of the substrate where the light-emitting chip is not grown by magnetron sputtering.

5. The chip transfer method as described in claim 1 or 4, characterized in that, The process of forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown includes: Based on the thickness of the substrate, its heat dissipation capacity, and the damage temperature of the light-emitting chip, a target thermochromic material is determined so that the preset temperature is lower than the damage temperature of the light-emitting chip. The thermochromic layer is formed using the target thermochromic material.

6. The chip transfer method as described in claim 1 or 4, characterized in that, Before forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown, the method further includes: Based on the heat dissipation capacity of the substrate, the abrupt change temperature of the thermochromic layer, and the damage temperature of the light-emitting chip, the target thickness of the substrate to be used is determined so that the preset temperature is less than the damage temperature of the light-emitting chip; the thermochromic layer reduces the transmittance of laser when its own temperature is higher than the abrupt change temperature. Before forming the thermochromic layer on the surface of the substrate on the side where the light-emitting chip is not grown, the method further includes: A substrate with a thickness equal to the target thickness is provided.

7. A substrate, characterized in that, A light-emitting chip is grown on one side of the substrate. A thermochromic layer is provided on the substrate on the surface of the side of the substrate where the light-emitting chip is not grown. The thermochromic layer is used to reduce the transmittance of the laser when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is higher than a preset temperature, and to maintain the transmittance of the laser when the interface temperature at the growth interface between the substrate and any of the light-emitting chips is lower than the preset temperature, so as to facilitate the peeling off of the light-emitting chip.

8. A display panel, characterized in that, The display panel includes a light-emitting chip and a circuit substrate, wherein the light-emitting chip is transferred to the die-bonding region of the circuit substrate by the chip transfer method according to any one of claims 1-6.

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