A Micro LED Chip Structure and Its Manufacturing Method

Abstract

This invention provides a Micro LED chip structure and its manufacturing method. First, an LED epitaxial wafer structure is grown on a first substrate. A patterned ohmic contact layer and a first electrode layer are fabricated on the epitaxial wafer structure. A second substrate is temporarily bonded to the first electrode layer side of the epitaxial wafer structure using an adhesive. The first substrate is removed. A patterned second electrode layer is fabricated on the epitaxial wafer structure on the side away from the second substrate using a double-sided alignment method with the patterned first electrode layer. During the above process, after fabricating the first or second electrode, an etching method is used to divide the epitaxial layer so that the Micro LED chips are arrayed on the first or second substrate. Finally, the adhesive is released using laser to peel the Micro LED chips off the second substrate, obtaining a thin-film Micro LED chip. This invention uses adhesive bonding and double-sided alignment photolithography to fabricate thin-film Micro LED chips, resulting in a simple fabrication process and high reliability of the thin-film chip structure.

Description

Technical Field

[0001] This application relates to the field of light-emitting devices, and in particular to an LED chip and its manufacturing method. Background Technology

[0002] Micro LED chips are thin-film, miniaturized light-emitting diodes. Each Micro LED chip unit emits light autonomously, exhibiting short response time and high luminous efficiency. This results in high resolution, high contrast, high color saturation, low power consumption, ultra-high resolution, and wide viewing angles, making them highly promising for applications in new LED displays, visual smart devices, and wearable devices. Existing AlGaInP-based Micro LED chips involve growing an epitaxial wafer on a temporary GaAs substrate, then bonding the epitaxial wafer to a transparent sapphire substrate. The epitaxial wafer is then peeled off, removing the GaAs substrate. The transparent sapphire substrate serves as a temporary support substrate for chip fabrication on the exposed epitaxial layer. This chip fabrication process often employs metal bonding and oxide bonding to transfer the epitaxial layer to the transparent sapphire substrate. This requires sophisticated bonding processes, and the existing horizontal chip structure limits current expansion, resulting in low luminous efficiency. Furthermore, the process is complex, the chip structure is easily damaged, large-area complete peeling is difficult, and mass transfer is challenging. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a micro LED chip and its manufacturing method, achieving a chip with simple manufacturing process, no damage to the chip structure, and high reliability.

[0004] This invention provides a method for manufacturing a micro LED chip, specifically including:

[0005] S1, an epitaxial wafer structure is grown on the first substrate; the epitaxial wafer structure includes a buffer layer, a barrier / sacrificial layer, an n-ohm contact layer, an n-type confinement layer, an MQW active layer, a p-type confinement layer and a p-type ohm contact window layer grown sequentially.

[0006] S2, a patterned p-ohm contact layer and a first electrode layer are formed on the epitaxial wafer structure in the direction away from the first substrate, and the first electrode layer is located on the p-ohm contact layer;

[0007] S3, a vertically segmented epitaxial wafer structure, which allows several Micro LED chips to be located in an array on the first substrate;

[0008] S4, temporarily bonding the second substrate to the first electrode layer side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding;

[0009] S5, using the second substrate as a temporary support substrate, the buffer layer and the barrier / sacrificial layer are etched to achieve the peeling off of the first substrate, and a number of Micro LED chips are located on the second substrate in an array;

[0010] S6, using the second substrate as a temporary support, a patterned second electrode layer is fabricated in the direction of the epitaxial structure away from the second substrate;

[0011] S7 uses a laser to act on the adhesive layer to peel the chip from the second substrate, thus fabricating a micro LED chip.

[0012] According to one embodiment of the present invention, in step S3, the epitaxial wafer is vertically divided to the upper surface of the barrier layer / sacrificial layer, the buffer layer, and the first substrate.

[0013] According to one embodiment of the present invention, after vertically dividing the epitaxial wafer structure in step S3, a first passivation protective layer is fabricated on the sidewall and upper surface of the Micro LED chip, exposing the first electrode portion that needs to be electrically connected.

[0014] According to one embodiment of the present invention, after the second electrode layer is fabricated in step S6, the adhesive layer between each microLED is vertically divided.

[0015] According to one embodiment of the present invention, the electrode layer of a Micro LED chip is prepared by double-sided alignment photolithography.

[0016] According to one embodiment of the present invention, the vertically segmented adhesive layer is produced using a combination of laser decomposition and dry etching.

[0017] According to one embodiment of the present invention, the adhesive is an ultraviolet adhesive. A 248nm wavelength laser is used to decompose the adhesive in the direction perpendicular to the electrode to ensure complete decomposition. A 355nm wavelength laser is used to decompose the remaining portion of the adhesive to achieve separation of the micro LED from the second substrate.

[0018] This invention provides another method for fabricating a micro LED chip, specifically including:

[0019] S1, an epitaxial wafer structure is grown on a first substrate; the epitaxial wafer structure includes a buffer layer, a barrier / sacrificial layer, an ohmic contact layer, an n-type confinement layer, an MQW active layer, a p-type confinement layer and a p-type ohmic contact window layer grown sequentially.

[0020] S2, a patterned p-ohm contact layer and a first electrode layer are formed on the epitaxial wafer structure in the direction away from the first substrate, and the first electrode layer is located on the p-ohm contact layer;

[0021] S3, temporarily bonding the second substrate to the first electrode layer side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding;

[0022] S4, using the second substrate as a temporary support substrate, etch the buffer layer and the barrier / sacrificial layer to achieve the peeling off of the first substrate;

[0023] S5, a patterned second electrode layer is fabricated in the direction of the epitaxial structure away from the second substrate;

[0024] S6, a vertically segmented epitaxial wafer structure, which allows several Micro LED chips to be located in an array on the second substrate;

[0025] S7 uses a laser to act on the adhesive layer to peel the chip from the second substrate, thus fabricating a micro LED chip.

[0026] According to one embodiment of the present invention, in step S6, the epitaxial wafer is vertically divided to the surface of the adhesive layer opposite to the second substrate or to the upper surface of the second substrate.

[0027] According to one embodiment of the present invention, after vertically dividing the epitaxial wafer structure in step S6, a second passivation protective layer is fabricated on the sidewall and upper surface of the Micro LED chip, exposing the second electrode portion that needs to be electrically connected.

[0028] According to one embodiment of the present invention, the electrode layers of each micro LED chip are prepared by double-sided alignment photolithography.

[0029] Both of the above manufacturing methods can include the following implementation methods:

[0030] According to one embodiment of the present invention, the contact layer is n-type AlGaInP, the n-type confinement layer is GaInP, the p-type GaInP confinement layer is GaInP, and the p-type ohmic contact window layer is GaP.

[0031] According to one embodiment of the present invention, the second substrate is selected as sapphire, glass, quartz, or a rigid material that can transmit light.

[0032] According to one embodiment of the present invention, the first substrate is selected as a GaAs substrate.

[0033] According to one embodiment of the present invention, the adhesive is a laser-decomposed polymer adhesive.

[0034] Furthermore, the laser-degradable adhesive is selected from ultraviolet photosensitive adhesives.

[0035] Furthermore, the adhesive layer thickness is 2.5-5 μm.

[0036] In another aspect, the present invention provides a micro LED chip manufactured by the above-described manufacturing method.

[0037] These and other aspects of this disclosure will become apparent from the following description of preferred embodiments in conjunction with the accompanying drawings and description, but variations and modifications may be made thereto without departing from the spirit and scope of the novel concept of this disclosure. Attached Figure Description

[0038] Figure 1 This is a structural diagram of the epitaxial wafer of the present invention;

[0039] Figures 2a-2f This is a structural diagram of the preparation process according to an embodiment of the present invention;

[0040] Figures 3a-3f This is a structural diagram of the preparation process according to another embodiment of the present invention;

[0041] List of reference numerals

[0042] 100 - First substrate, 101 - Buffer layer, 102 - Barrier layer / Sacrificial layer, 103 - n-ohmic contact layer, 104 - n-type confinement layer, 105 - MQW active layer, 106 - p-type confinement layer, 107 - p-type ohmic contact window layer, 201 - First electrode layer, 202 - First passivation protection layer, 301 - Adhesive layer, 302 - Second substrate, 401 - Second electrode layer, 402 - Second passivation protection layer. Detailed Implementation

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the drawings, components with the same or similar functions are represented by the same or similar reference numerals. Furthermore, some components not directly related to the inventive concept may be omitted from the illustrations. The description of the accompanying drawings and specific embodiments is only for a better understanding of the present invention, and the present invention is not limited to the embodiments illustrated in the drawings and described in the specification.

[0044] The technical or scientific terms used in this invention should be understood in their ordinary sense by one of ordinary skill in the art. The use of terms such as "comprising" or "including" in this invention indicates an open meaning, excluding other elements, components, parts, or items besides those explicitly listed. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positions may change accordingly when the absolute position of the described object changes. Terms such as "first" and "second" are used to distinguish different components and do not indicate a specific order.

[0045] See Figure 1 , Figures 2a-2f According to an embodiment of this application, a method for fabricating a micro LED chip, a vertically structured micro LED, includes the following steps:

[0046] Step S1, see Figure 1 An epitaxial wafer structure is grown on the first substrate 100. The epitaxial wafer structure includes a buffer layer 101, a barrier / sacrificial layer 102, an n-ohm contact layer 103, an n-type confinement layer 104, an MQW active layer 105, a p-type confinement layer 106, and a p-type ohm contact window layer 107 grown sequentially.

[0047] The barrier layer / sacrificial layer 102 is subsequently used to separate the epitaxial wafer from the first substrate 100, which is a GaAs substrate or other substrates suitable for growing epitaxial structures.

[0048] The n-type confinement layer 104, the MQW active layer 105, and the p-type confinement layer 106 form the main working parts of the LED. High-concentration electrons and holes are injected into the MQW active layer 105 from the n-type confinement layer 104 and the p-type confinement layer 106, respectively, and recombine to generate photons, thus achieving electro-optical conversion. Taking a red LED as an example, the confinement layer can be selected as AlInP, AlGaInP, etc., and the MQW multilayer quantum well can be selected as AlGaInP, GaAs, etc. The ohmic contact window layer is used to increase current spread; taking a red LED as an example, GaP, AlGaAs, or transparent conductive oxides can be selected. The sacrificial layer can be selected as AlAs / AlGaAs, and the blocking layer can be selected as GaInP.

[0049] Step S2, see Figure 2a A patterned ohmic contact layer and a first electrode layer 201 are fabricated on the epitaxial wafer structure in the direction away from the first substrate, with the first electrode layer 201 located on the ohmic contact layer.

[0050] Using photolithography, a patterned ohmic contact layer is formed, and an electrode layer is deposited on the ohmic contact layer. The pattern of the ohmic contact layer is the same as that of the electrode layer. Each independent electrode region in the pattern constitutes the electrode region of a micro LED chip. The ohmic contact layer ensures low contact resistance between the electrode and the epitaxial structure and ensures efficient electron-hole injection, thereby improving LED efficiency. For the selection of materials for the ohmic contact layer and the first electrode layer, taking a red light-emitting diode as an example, GaAs can be selected, and the electrodes can be selected from materials such as Ti, Ge, Pt, Ni, and Au.

[0051] Step S3, see Figure 2b The vertically segmented epitaxial wafer structure allows several Micro LED chips to be arrayed on the first substrate 100. A first passivation protection layer 202 is fabricated on the sidewalls and surface of the Micro LED chips, exposing the first electrode portion that needs to be electrically connected.

[0052] Specifically, using photolithography, wet etching or dry etching is selected to cut the epitaxial layer to the upper surface of the barrier / sacrificial layer 102, the upper surface of the buffer layer 101, or the upper surface of the first substrate 100. Several Micro LED chips are arranged in an array on the first substrate 100 to facilitate subsequent peeling. Next, a first passivation protection layer 202 is prepared on the micro LED array. The material of the first passivation protection layer 202 is one or more of SiO2, Al2O3, and Si3N4. The first passivation protection layer 202 is located on the side and upper surface of the Micro LED chip, covering part of the electrode and exposing the part of the electrode that needs to be electrically connected.

[0053] Step S4: Temporarily bond the second substrate 302 to the electrode side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding, see details below. Figure 2c .

[0054] The second substrate 302 can be made of sapphire, glass, or quartz, preferably a rigid material that transmits light. An adhesive is applied to one side of the substrate to bond the second substrate 302 to the electrode of the epitaxial wafer. To ensure a smooth interface, a certain pressure can be applied. The second substrate 302 serves as a support structure for subsequent epitaxial layer peeling and transfer, as well as for subsequent processing of the epitaxial wafer. The adhesive can be a laser-decomposed polymer adhesive, which has a significantly reduced viscosity after laser action, facilitating the detachment of the micro LED chip particles.

[0055] The thickness of the adhesive layer 301 in this invention is preferably 2.5µm to 5µm. The adhesive weakly bonds the second substrate 302 and the chip. If the adhesive layer is too thin, the bonding effect is poor, failing to effectively fix the second substrate 302 and the chip, which is detrimental to subsequent processes such as the removal of the first substrate. If the adhesive layer is too thick, higher laser power and longer decomposition time are required during subsequent laser decomposition, easily generating more heat, and more adhesive residue remains on the chip surface after separation from the second substrate 302, hindering cleaning. Therefore, for conventional Micro LED chips ranging from 1 to tens of micrometers, this invention, through experimental verification, selects an adhesive layer thickness of 2.5µm to 5µm, which effectively achieves bonding between the second substrate 302 and the chip and subsequent laser decomposition.

[0056] In step S5, using the second substrate 302 as a temporary support substrate, the buffer layer and the barrier / sacrificial layer are etched to peel off the first substrate 100, and a number of Micro LED chips are located on the second substrate 302 in an array.

[0057] In one embodiment, the semiconductor chip epitaxial wafer is peeled off from the first substrate 100 by etching and cleaning the sacrificial layer 102 with a first etchant. Here, the first etchant may be a solution that selectively etches the sacrificial layer 102 and the semiconductor chip epitaxial wafer, that is, the first etchant can etch the sacrificial layer but not the semiconductor chip epitaxial wafer. Alternatively, other processes may be used to remove the sacrificial layer 102 and the first substrate 100, and a plurality of Micro LED chips are arranged in an array on the second substrate 302.

[0058] In another embodiment, for the barrier layer, a second solution is used to etch the first substrate 100 to remove the first substrate 100, and then a third etchant is used to etch the barrier layer, with a plurality of Micro LED chips located on the second substrate 302 in an array.

[0059] For example, gallium arsenide is used as the first substrate 100. A mixture of phosphoric acid and hydrogen peroxide is used to remove the gallium arsenide substrate. Then, a mixture of nitric acid and hydrochloric acid is used to etch and remove the barrier layer GaInP, thereby peeling off the first substrate 100 and obtaining an epitaxial wafer with a second substrate 302.

[0060] Step S6: Using the second substrate 302 as a temporary support, a patterned second electrode layer 401 is fabricated in the direction away from the second substrate 302 of the epitaxial structure. See details below. Figure 2d ;

[0061] Using photolithography, a patterned second electrode layer 401 is formed. Each independent second electrode region in the pattern, together with the corresponding first electrode region in the vertical direction of step S2, constitutes the two electrodes of the vertical micro LED chip. To ensure the above correspondence of the micron-sized micro LED chip, double-sided alignment photolithography is used to ensure precise alignment of the patterns processed on both sides of the epitaxial wafer. Specifically, alignment markings are used, which can be made on the epitaxial wafer and the photomask to achieve the above alignment. The marking method can be any shape, such as a cross, a square, or a circle. The size and position of the two electrodes can be selected according to specific requirements.

[0062] Furthermore, to facilitate subsequent peeling, after fabricating the second electrode layer 401, the adhesive layer 301 between the microLEDs can be vertically separated. Specifically, it can be separated to the upper surface of the second substrate 302, and dry etching can be used. See [link to documentation]. Figure 2e .

[0063] Preferably, a combination of dry etching and laser etching can be used to separate the adhesive layer 301 between LED chips. First, laser decomposition is used for coarse separation. Laser decomposition has high decomposition efficiency, but gas accumulation occurs during the decomposition process, affecting the cutting efficiency. Therefore, after laser coarse separation, dry etching is used for further separation. During the dry etching process, the generated gas can be extracted. It can be seen that the combination of the two can achieve a higher cutting efficiency.

[0064] S7. A laser is used to act on the adhesive layer 301 to peel the chip from the second substrate 302, thus fabricating a micro LED chip.

[0065] In one embodiment, the second substrate 302 is irradiated with a laser, causing the adhesive to decompose, reducing its stickiness and weakening its bonding force, causing the chip particles to detach and be transferred to other substrates.

[0066] Furthermore, the entire epitaxial wafer chip can be irradiated with a laser to cause the entire chip to detach. Alternatively, partial detachment can be selected. Specifically, a mask is prepared with transparent and opaque areas. By setting the mask opaque for the chip that does not need to be placed, and setting the transparent area for the chip that needs to be placed, the adhesive decomposes under laser irradiation, reducing its viscosity and weakening its bonding force, causing the chip to detach and be transferred to other substrates, thus achieving chip detachment and transfer.

[0067] Furthermore, for the ultraviolet adhesive, 355nm and 248nm lasers can be used for decomposition. The ultraviolet adhesive has a high absorption rate at 355nm, providing a relatively gentle energy release; the 248nm wavelength is shorter, providing higher resolution and a smaller heat-affected zone, suitable for higher precision scenarios. Based on the above principles, this invention selects a 248nm wavelength to decompose the ultraviolet adhesive in the direction perpendicular to the electrode, ensuring complete decomposition of the adhesive and facilitating subsequent electrode electrical connection; a 355nm wavelength is used to decompose the remaining parts, achieving the purpose of separating the chip and the second substrate. For residual adhesive on the chip, cleaning can be selected as needed.

[0068] This invention involves fabricating a patterned chip first ohmic contact layer and an electrode layer on an epitaxial wafer. A temporary adhesive method is used to bond one side of the chip electrode layer of the epitaxial wafer to a second substrate 302. The adhesive's strength and adhesion facilitate laser irradiation for peeling off the second substrate 302. On one hand, the second substrate 302 serves as a supporting substrate for peeling off the first substrate 100 from the epitaxial wafer, enabling the transfer of the epitaxial wafer and subsequent processing such as the fabrication of the second electrode, allowing the micro LED chips to exist separately on the second substrate 302. On the other hand, the second substrate 302, acting as a temporary substrate, allows the micro LED chip particles to detach via laser peeling, achieving particle transfer. This invention achieves the fabrication and transfer of micro LED chip particles through the use of two temporary substrates, namely the first substrate and the second substrate 302. Compared to conventional processes that require multiple temporary substrate setups for epitaxial wafer flipping, processing, and micro LED chip detachment, this simplifies the fabrication process. Furthermore, the adhesive method avoids damage to the chip film caused by uneven bonding interfaces during the peeling process in traditional bonding processes, thus improving the reliability of the thin-film chip structure.

[0069] The vertical structure Micro LED chip described in the above embodiment of the invention employs a double-sided alignment method to fabricate electrodes and contact layers on the epitaxial wafer and perform segmentation, so that the Micro LED chip array is located on the substrate, followed by chip separation. Using this double-sided alignment method ensures precise alignment of the two surfaces of the epitaxial wafer at the micro-nano scale, fabricating high-precision electrodes, ensuring accurate alignment and electrical connection of each LED unit, and improving the uniformity and performance of the overall array.

[0070] See Figures 3a-3f According to another embodiment of the present application, the method for manufacturing a micro LED chip differs from that of embodiment 1 in that the chip dicing step is set after the first substrate is peeled off, and the light-emitting surface of the micro LED chip is different from that of embodiment 1.

[0071] Specifically, the following steps are included:

[0072] Step S1: An epitaxial wafer structure is grown on the first substrate 100. The epitaxial wafer structure includes a buffer layer 101, a barrier / sacrificial layer 102, an n-ohm contact layer 103, an n-type confinement layer 104, an MQW active layer 105, a p-type confinement layer 106, and a p-type ohm contact window layer 107 grown sequentially.

[0073] Step S2, as follows Figure 3a As shown, a patterned ohmic contact layer and a first electrode layer 201 are formed on the epitaxial wafer structure in the direction away from the first substrate 100, with the first electrode layer 201 located on the ohmic contact layer.

[0074] The specific operations of steps S1 and S2 involve the same material selection and working principle as steps S1 and S2 in the previous embodiment, and will not be repeated here.

[0075] Step S3, as follows Figure 3b As shown, the second substrate 302 is temporarily bonded to the first electrode layer 201 side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding, and the second substrate 302 is connected through the adhesive layer 301.

[0076] The specific operation of this step involves the same material selection and preparation process as step S4 in the previous embodiment, and will not be repeated here.

[0077] Step S4: Using the second substrate 302 as a temporary support substrate, the buffer layer and the barrier / sacrificial layer are etched to achieve the peeling off of the first substrate;

[0078] The specific operation of this step involves the same corrosion principle and selection of corrosion solution as step S5 in the previous embodiment.

[0079] Step S5, as follows Figure 3c As shown, a patterned second electrode layer 401 is formed in the direction away from the second substrate 302 of the epitaxial structure;

[0080] Using photolithography, a patterned second electrode layer 401 is formed. Each independent second electrode region in the pattern, together with the corresponding first electrode region in the vertical direction of step S2, constitutes the two electrodes of the vertical micro LED chip. To ensure the above correspondence of the micron-sized micro LED chip, double-sided alignment photolithography is used to ensure precise alignment of the patterns processed on both sides of the epitaxial wafer. Specifically, alignment markings are used, which can be made on the epitaxial wafer and the photomask to achieve the above alignment. The marking method can be any shape, such as a cross, a square, or a circle. The size and position of the two electrodes can be selected according to specific requirements.

[0081] Step S6, as follows Figures 3d-3eAs shown, the vertically segmented epitaxial wafer structure allows several Micro LED chips to be arrayed on the second substrate 302. A first passivation protection layer 202 is fabricated on the sidewalls and surface of the Micro LED chips, exposing the electrode portions that need to be electrically connected.

[0082] Specifically, in conjunction with photolithography technology, either wet etching or dry etching methods are selected, such as... Figure 3d As shown, the epitaxial layer is cut to the upper surface of the second substrate 302, and the adhesive colloid is also cut away from the upper surface of the second substrate 302. Several Micro LED chips are arranged in an array on the first substrate 100 to facilitate subsequent peeling. Then, a second passivation protection layer 402 is prepared on the micro LED array. The second passivation protection layer 402 is located on the side and upper surface of the Micro LED chip, covering part of the electrode and exposing the part of the electrode that needs to be electrically connected.

[0083] Step S7, as follows Figure 3f As shown, a laser is used to act on the adhesive layer 301 to peel the chip from the second substrate 302, thus fabricating micro LED chip particles.

[0084] The specific stripping process involved in this step is the same as step S7 in the previous embodiment, and will not be described again here.

[0085] The following will illustrate the fabrication process of a micro LED chip according to one embodiment of the present invention with specific examples.

[0086] Step S1: Using GaAs as a temporary substrate, GaAs buffer layer, sacrificial AlAs layer, n-type AlGaInP ohmic contact layer 103, n-type GaInP confinement layer, MQW active layer 105, p-type GaInP confinement layer and p-type GaP ohmic contact window layer are grown by metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0087] Step S2: A patterned GaAs ohmic contact layer and a first Au electrode layer are fabricated on the epitaxial wafer structure in the direction away from the first substrate, with the first electrode layer located on the ohmic contact layer.

[0088] Step S3: Vertically divide the epitaxial wafer structure so that a plurality of Micro LED chips are located on the first substrate 100 in an array, and fabricate a first passivation protection layer 202 on the sidewalls and surface of the Micro LED chips, exposing the first electrode portion that needs to be electrically connected.

[0089] Specifically, dry or wet cutting is used, and time and other conditions are controlled to cut the epitaxial layer to the upper surface of the barrier layer, the upper surface of the buffer layer, or the upper surface of the temporary GaAs substrate. A first passivation protection layer 202 is prepared on the side and upper surface of the micro LED using photolithography. The material of the first passivation protection layer 202 is one or more of SiO2, Al2O3, and Si3N4. The passivation layer protects part of the electrode, exposing the part of the electrode that needs to be electrically connected.

[0090] Step S4: Temporarily bond the glass substrate coated with UV photosensitive adhesive to the electrode side of the epitaxial wafer structure.

[0091] In step S5, using a glass substrate as a temporary support substrate, the barrier layer and the substrate are etched to achieve GaAs substrate peeling, and several Micro LED chips are located on the glass substrate in an array.

[0092] Step S6: Using a glass substrate as a temporary support, a patterned second electrode layer 401 is fabricated in the direction away from the glass substrate of the epitaxial structure. The metal material can be selected as Au, Ag, Ni, Cu, Al, etc.; preferably, the adhesive between the Micro LED chips is cut by laser decomposition and dry etching assembly method.

[0093] Step S7: Use a laser to peel the chip from the glass substrate to fabricate micro LED chip particles.

[0094] The fabrication process of a micro LED chip according to another embodiment of the present invention will be described with reference to specific examples.

[0095] Step S1: Using GaAs as a temporary substrate, GaAs buffer layer, sacrificial AlAs layer, n-type AlGaInP ohmic contact layer 103, n-type GaInP confinement layer, MQW active layer 105, p-type GaInP confinement layer and p-type GaP ohmic contact window layer are grown by metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0096] Step S2: A patterned GaAs ohmic contact layer and a first Au electrode layer are fabricated on the epitaxial wafer structure in the direction away from the GaAs substrate, with the first electrode layer located on the ohmic contact layer.

[0097] Step S3: Temporarily bond the glass substrate coated with UV photosensitive adhesive to the first Au electrode layer side of the epitaxial wafer structure.

[0098] Step S4: Using a glass substrate as a temporary support substrate, the barrier layer and the substrate are etched to achieve GaAs substrate peeling, and several Micro LED chips are located on the glass substrate in an array.

[0099] Step S5: Using a glass substrate as a temporary support, a patterned second electrode layer 401 is fabricated in the direction away from the glass substrate of the epitaxial structure. The metal material can be selected from Au, Ag, Ni, Cu, Al, etc.

[0100] Step S6: Vertically divide the epitaxial wafer structure so that several Micro LED chips are located on the glass substrate in an array. Fabricate a second passivation protection layer 402 on the sidewalls and surface of the Micro LED chips, exposing the second electrode portion that needs to be electrically connected.

[0101] Step S7: Use a laser to peel the chip from the glass substrate to fabricate micro LED chip particles.

[0102] The foregoing description of exemplary embodiments of this disclosure is for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit this disclosure to the precise forms disclosed. Many modifications and variations are possible in accordance with the foregoing teachings. The embodiments were chosen and described to explain the principles of this disclosure and its practical application, so that others skilled in the art can utilize this disclosure and various embodiments with various modifications suitable for the particular purpose contemplated. Alternative embodiments will become apparent to those skilled in the art to which this disclosure pertains without departing from the spirit and scope of this disclosure. Therefore, the scope of this disclosure is defined by the appended claims rather than by the foregoing description and the exemplary embodiments described therein.

Claims

1. A method for fabricating a micro LED chip, specifically comprising: S1, an epitaxial wafer structure is grown on the first substrate; the epitaxial wafer structure includes a buffer layer, a barrier / sacrificial layer, an n-ohm contact layer, an n-type confinement layer, an MQW active layer, a p-type confinement layer and a p-type ohm contact window layer grown sequentially. S2, a patterned p-ohm contact layer and a first electrode layer are formed on the epitaxial wafer structure in the direction away from the first substrate, and the first electrode layer is located on the p-ohm contact layer; S3, vertically divide the epitaxial wafer structure so that several Micro LED chips are located on the first substrate in an array. Vertically divide the epitaxial wafer to the barrier layer / sacrificial layer, buffer layer, and the upper surface of the first substrate. After vertically dividing the epitaxial wafer structure, a first passivation protection layer is made on the sidewall and upper surface of the Micro LED chip, exposing the first electrode part that needs to be electrically connected. S4, temporarily bonding the second substrate to the first electrode layer side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding; S5, using the second substrate as a temporary support substrate, the buffer layer and the barrier / sacrificial layer are etched to achieve the peeling off of the first substrate, and a number of Micro LED chips are located on the second substrate in an array; S6, using the second substrate as a temporary support, a patterned second electrode layer is fabricated in the direction of the epitaxial structure away from the second substrate, and then the adhesive layer between the micro LEDs is vertically divided. S7 uses a laser to act on the adhesive layer to peel the chip from the second substrate, thus fabricating a micro LED chip.

2. The manufacturing method according to claim 1, wherein, The vertically segmented adhesive layer is produced using a combination of laser decomposition and dry etching.

3. The manufacturing method according to claim 1, wherein the adhesive is an ultraviolet adhesive, a 248nm wavelength laser is used to decompose the adhesive in the direction perpendicular to the electrode to ensure complete decomposition, and a 355nm wavelength laser is used to decompose the remaining adhesive to achieve separation of the micro LED from the second substrate.

4. A method for fabricating a micro LED chip, comprising: S1, an epitaxial wafer structure is grown on the first substrate; the epitaxial wafer structure includes a buffer layer, a barrier / sacrificial layer, an n-ohm contact layer, an n-type confinement layer, an MQW active layer, a p-type confinement layer and a p-type ohm contact window layer grown sequentially. S2, a patterned p-ohm contact layer and a first electrode layer are formed on the epitaxial wafer structure in the direction away from the first substrate, and the first electrode layer is located on the p-ohm contact layer; S3, temporarily bonding the second substrate to the first electrode layer side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding; S4, using the second substrate as a temporary support substrate, etch the buffer layer and the barrier / sacrificial layer to achieve the peeling off of the first substrate; S5, a patterned second electrode layer is fabricated in the direction away from the second substrate of the epitaxial wafer structure; S6, vertically divide the epitaxial wafer structure so that several Micro LED chips are located on the second substrate in an array, and then a second passivation protective layer is fabricated on the sidewall and upper surface of the Micro LED chips, exposing the second electrode portion that needs to be electrically connected. S7 uses a laser to act on the adhesive layer to peel the chip from the second substrate, thus fabricating a micro LED chip.

5. The manufacturing method according to claim 4, wherein, In step S6, the epitaxial wafer is vertically divided to the surface of the adhesive layer facing away from the second substrate or to the upper surface of the second substrate.

6. The manufacturing method according to any one of claims 1-5, wherein, Electrode layers for each microLED chip are fabricated using double-sided alignment photolithography.

7. The manufacturing method according to any one of claims 1-5, wherein, The adhesive is a laser-decomposed polymer adhesive, and the polymer adhesive is a UV-sensitive adhesive.

8. The manufacturing method according to any one of claims 1-5, wherein the adhesive layer thickness is 2.5-5 μm.

9. A micro LED chip manufactured using the method described in any one of claims 1-8.

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