Micro LED chip structure and manufacturing method thereof

Abstract

The invention provides a Micro LED chip structure and a manufacturing method thereof. The manufacturing method comprises the following steps: firstly, growing an LED epitaxial wafer structure on a first substrate; manufacturing a patterned ohmic contact layer and a first electrode layer on the epitaxial wafer structure; temporarily bonding a second substrate to the first electrode layer side of the epitaxial wafer structure through an adhesive; removing the first substrate; and manufacturing a patterned second electrode layer on the epitaxial wafer structure on one side far away from the second substrate in a manner of double-sided alignment with the patterned first electrode layer. In the process, after the first electrode or the second electrode is prepared, the epitaxial layer is segmented by adopting an etching method, so that the Micro LED chips are positioned on the first substrate or the second substrate in an array form. And finally, removing the bonding effect of the bonding agent through laser, and stripping the Micro LED chip from the second substrate to obtain the thin film type Micro LED chip. According to the invention, the film type Micro LED chip is prepared by adopting adhesive bonding and a double-sided alignment photoetching method, the manufacturing process is simple, and the film type chip structure is high in reliability.

Description

Technical Field

[0001] The present application relates to the field of light-emitting devices, and in particular to an LED chip and a method for manufacturing the same. Background Art

[0002] Micro LED chip is a thin-film, miniaturized light-emitting diode. Each Micro LED chip unit emits light autonomously, has a short response time, and high light efficiency, thus achieving high resolution, high contrast, high color saturation, low power consumption, ultra-high resolution, and wide viewing angle display effects. It has great application prospects in the fields of new LED display screens, visual smart devices, wearable devices, etc. The existing AlGaInP-based Micro LED chip grows an epitaxial wafer on a temporary GaAs substrate, and then bonds the epitaxial wafer to a transparent sapphire substrate for epitaxial wafer peeling, and then removes the GaAs substrate. The transparent sapphire substrate is used as a temporary supporting substrate to process the chip on the exposed epitaxial layer. In the above chip preparation process, metal bonding, oxide bonding and other processes are often used to transfer the epitaxial layer to the transparent sapphire substrate. The bonding process has high requirements, and the existing horizontal structure chip limits the current expansion, has low light efficiency, and has problems such as complex processing technology, easy damage to the chip structure, difficulty in large-scale complete peeling, and difficulty in mass transfer. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a micro LED chip and a method for manufacturing the same, so as to realize a chip with a simple manufacturing process, no damage to the chip structure, and high reliability.

[0004] The present invention provides a method for manufacturing a micro LED chip, which specifically includes:

[0005] S1, growing an epitaxial wafer structure on a first substrate; the epitaxial wafer structure includes sequentially growing a buffer layer, a barrier layer / sacrificial layer, an n-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;

[0006] S2, forming a patterned p-ohmic contact layer and a first electrode layer in the direction of the epitaxial wafer structure away from the first substrate, wherein the first electrode layer is located on the p-ohmic contact layer;

[0007] S3, vertically dividing the epitaxial wafer structure so that a plurality of Micro LED chips are arranged on the first substrate in an array form;

[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, etching the sacrificial layer or etching the substrate and the barrier layer to peel off the first substrate, and placing a plurality of Micro LED chips in an array on the second substrate;

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

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

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

[0013] According to an embodiment of the present invention, after the epitaxial wafer structure is vertically divided in the step S3, a passivation protection layer is formed on the sidewalls and the upper surface of the Micro LED chip to expose 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 bonding layer between each microLED is vertically divided.

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

[0016] According to one embodiment of the present invention, the vertical segmentation of the adhesive layer adopts a process combining laser decomposition and dry etching.

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

[0018] The present invention provides another method for manufacturing a micro LED chip, which specifically includes:

[0019] S1, growing an epitaxial wafer structure on a first substrate; the epitaxial wafer structure includes sequentially growing a buffer layer, a barrier layer / 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;

[0020] S2, forming a patterned p-ohmic contact layer and a first electrode layer in the direction of the epitaxial wafer structure away from the first substrate, wherein the first electrode layer is located on the p-ohmic 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 supporting substrate, etching the sacrificial layer or etching the substrate and the barrier layer to realize substrate peeling of the first substrate;

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

[0024] S6, vertically dividing the epitaxial wafer structure so that a plurality of Micro LED chips are arranged on the second substrate in an array form;

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

[0026] According to an embodiment of the present invention, in the step S6, the epitaxial wafer is vertically divided to the surface of the bonding layer facing away from the second substrate or to the upper surface of the second substrate.

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

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

[0029] For the above two production methods, both may include the following implementation methods:

[0030] According to an embodiment of the present invention, the contact layer 103 is n-type AlGaInP, the n-type confinement layer 104 is GaInP, the p-type GaInP confinement layer 106 is GaInP, and the p-type ohmic contact window layer is GaP.

[0031] According to an embodiment of the present invention, the second substrate is selected from sapphire, glass, quartz, and other rigid materials that can transmit light.

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

[0033] According to an embodiment of the present invention, the adhesive glue is a polymer glue decomposed by laser.

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

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

[0036] In another aspect of the present invention, a micro LED chip manufactured by the above manufacturing method is provided.

[0037] These and other aspects of the disclosure will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings and description thereof, but variations and modifications may be made thereto without departing from the spirit and scope of the novel concepts of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0039] FIG2 is a structural diagram of a preparation process according to an embodiment of the present invention;

[0040] FIG3 is a structural diagram of a preparation process of another embodiment of the present invention;

[0041] Reference numerals list

[0042] 100 - first substrate, 101 - growth buffer layer, 102 - barrier layer, 103 - n-type 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, 202 - passivation protection layer, 301 - adhesive layer, 302 - second substrate, 401 - second electrode layer. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the exemplary embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the accompanying drawings, components with the same or similar functions are indicated by the same or similar reference numerals. In addition, some components that are not directly related to the concept of the present invention may be omitted from the illustration. The description of the 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 terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The use of "including" or "comprising" and similar words in the present invention indicates an open meaning, and does not exclude other elements, components, parts or items except for the elements, parts, parts or items clearly listed. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. "First", "second" and the like are used to distinguish different components and do not indicate a specific order.

[0045] See also Figure 1 -2. According to a method for manufacturing a micro LED chip according to an embodiment of the present application, a micro LED with a vertical structure is prepared, comprising the following steps:

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

[0047] The barrier layer or sacrificial layer 102 is subsequently used to peel off the epitaxial wafer and the first substrate 100 . The first substrate 100 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 are the main working parts of the LED. High-concentration electrons and holes are injected from the n-type confinement layer 104 and the p-type confinement layer 106 regions into the MQW active layer for recombination, generating photons and realizing electrical-optical conversion. Taking the red light emitting diode as an example, the confinement layer can be selected as AlInP, AlGaInP, etc., and the MQW multi-layer quantum well can be selected as AlGaInP, GaAs, etc. The ohmic contact window layer is used to increase the current expansion. Taking the red light emitting diode as an example, GaP, AlGaAs, and transparent conductive oxide can be selected. The sacrificial layer can be selected as AlAs\AlGaAs, and the barrier 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 in the direction of the epitaxial wafer structure away from the first substrate, and the first electrode layer 201 is located on the ohmic contact layer.

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

[0051] Step S3, see Figure 2b The epitaxial wafer structure is vertically divided so that a plurality of Micro LED chips are arranged in an array on a first substrate, and a passivation protection layer is formed on the sidewalls and surfaces of the Micro LED chips to expose a first electrode portion that needs to be electrically connected.

[0052] Specifically, in combination with photolithography technology, wet etching or dry etching is selected to cut the epitaxial layer to the upper surface of the barrier layer / 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 located on the first substrate in an array form to facilitate subsequent peeling. Next, a passivation protective layer 202 is prepared on the micro LED array. The material of the protective layer 202 is one or more of SiO2, Al2O3, and Si3N4. The passivation protective layer 202 is located on the side and upper surface of the Micro LED chip, wrapping part of the electrode to expose the part of the electrode that needs to be electrically connected.

[0053] Step S4, temporarily bonding the second substrate to the electrode side of the epitaxial wafer structure, wherein the temporary bonding is adhesive bonding, see Figure 2c .

[0054] Select a second substrate, which may be sapphire, glass, or quartz, preferably a rigid material that can transmit light. Apply adhesive on one side of the substrate and bond the second substrate to the electrode end of the epitaxial wafer. To ensure a smooth interface, a certain amount of pressure may be applied. The second substrate serves as a supporting structure for subsequent epitaxial layer peeling and transfer and subsequent processing of the epitaxial wafer. The adhesive may be a polymer glue that can be decomposed by laser. The viscosity decreases significantly after the laser action, making it easier for the micro LED chip particles to detach.

[0055] The thickness of the adhesive coating layer of the present invention is preferably 2.5um to 5um. The second substrate and the chip are weakly bonded by the adhesive. If the adhesive coating is too thin, the bonding effect is poor, and the second substrate and the chip cannot be effectively fixed, which is not conducive to subsequent processing such as peeling off the first substrate; if the adhesive coating is too thick, a higher laser power and a longer decomposition time need to be selected in the subsequent laser decomposition process, which is easy to generate more heat, and after the chip is separated from the subsequent second substrate, there are more adhesive residues attached to the chip surface, which is not conducive to cleaning. Therefore, for conventional Micro LED chips of 1 to more than ten microns, the present invention has verified through experiments that the thickness of the adhesive coating layer is selected to be 2.5um to 5um, which can effectively achieve the bonding of the second substrate and the chip and the subsequent laser decomposition.

[0056] Step S5, using the second substrate as a temporary supporting substrate, etching the sacrificial layer or etching the substrate and the barrier layer to realize substrate peeling of the first substrate, and a plurality of Micro LED chips are arranged on the second substrate in an array form.

[0057] In one embodiment, the sacrificial layer 102 is cleaned by etching with a first etching solution, and the semiconductor chip epitaxial wafer is peeled off from the first substrate 100; here, the first etching solution can be selected to have a selective etching solution for the sacrificial layer 102 and the semiconductor chip epitaxial wafer, that is, the first etching solution can corrode the sacrificial layer but not the semiconductor chip epitaxial wafer. Alternatively, other processes can 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.

[0058] In another embodiment, the barrier layer is etched with a second solution to remove the first substrate, and then a third etching solution is used to etch the barrier layer. A plurality of Micro LED chips are arranged in an array on the second substrate.

[0059] For example, gallium arsenide is used as the first substrate, and 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 stripping the substrate and obtaining an epitaxial wafer with a second substrate.

[0060] Step S6, using the second substrate as a temporary support, a patterned second electrode layer is formed in the direction of the epitaxial structure away from the second substrate, for details, see Figure 2d ;

[0061] Using photolithography technology, a graphic second electrode layer is formed. Each independent second electrode area in the pattern and the first electrode area corresponding to the vertical direction in step S2 together constitute two electrodes of the vertical micro LED chip. In order to ensure the above correspondence of the micron-sized micro LED chip, double-sided alignment lithography is used to ensure the precise alignment of the double-sided processing patterns of the epitaxial wafer. Specifically, an alignment mark method is used, and marking can be selected on the epitaxial wafer and the photolithography mask to achieve the above alignment. The marking method can be selected in the form of a cross, a square, a circle, etc. The size and position of the above two electrodes can be selected according to specific needs.

[0062] Further, in order to facilitate subsequent peeling, after the second electrode layer 401 is formed, the adhesive layer between the microLEDs can be vertically split, specifically, the splitting can be selected to the upper surface of the second substrate, and dry etching can be selected, see Figure 2e .

[0063] Preferably, dry etching combined with laser can be used to split the adhesive layer 301 between the LED chips. First, laser decomposition is used for rough splitting. Laser decomposition has a high decomposition efficiency, but gas is aggregated during the decomposition process, affecting the cutting efficiency. Therefore, after rough splitting with laser, dry etching is used for further splitting. The gas generated during the dry etching process can be extracted and processed. It can be seen that the combination of the two can achieve more efficient cutting.

[0064] S7 uses laser to act on the adhesive to peel the chip from the second substrate to make a micro LED chip.

[0065] In one embodiment, laser is used to irradiate the second substrate, so that the adhesive is decomposed, the viscosity is reduced, the bonding force is weakened, and the chip particles fall off and can be transferred to other substrates.

[0066] Furthermore, the entire epitaxial wafer chip can be irradiated with laser to make the particles fall off as a whole. Partial shedding can also be selected, specifically by preparing a mask plate with light-transmitting and light-impermeable areas, by setting the mask plate to be light-impermeable at the corresponding position of the chip that does not need to be put down, and setting the corresponding position of the chip that needs to be put down to be a light-transmitting area. Under laser irradiation, the adhesive decomposes, the viscosity decreases, the bonding force weakens, the chip particles fall off, and they can be transferred to other substrates, realizing the shedding and transfer of chip particles.

[0067] Furthermore, for ultraviolet adhesives, 355nm and 248nm lasers can be used for decomposition. Ultraviolet adhesives have a higher absorption rate for 355nm and provide a more gentle energy release; 248nm has a shorter wavelength and can provide higher resolution and a smaller heat-affected zone, which is suitable for higher-precision scenarios. Based on the above principles, the present invention chooses to use a 248nm wavelength to decompose the ultraviolet adhesive in the vertical direction of the electrode, so that the adhesive is completely decomposed, which is convenient for subsequent electrical connection of the electrodes; 355nm is used to decompose the remaining parts to achieve the purpose of separating the chip and the second substrate. For the residual adhesive on the chip, it can be selected whether to clean it according to the situation.

[0068] The embodiment of the present invention manufactures the first ohmic contact layer and electrode layer of the patterned chip on the epitaxial wafer, and uses a temporary bonding method to bond one side of the chip electrode layer of the epitaxial wafer to the second substrate. Since the adhesive has a certain strength and adhesion, it is convenient to peel off the second substrate by laser irradiation. On the one hand, the second substrate can be used as a supporting substrate to peel off the first substrate of the epitaxial wafer, realize the transfer of the epitaxial wafer, and perform subsequent second electrode preparation and other processing on the epitaxial wafer so that the mocro LED chips are separated from each other and exist on the second substrate; on the other hand, the second substrate is used as a temporary substrate to make the micro LED chip particles fall off through laser peeling to realize the transfer of particles. The present invention realizes the preparation and transfer of micro LED chip particles by setting two temporary substrates, namely the first substrate and the second substrate. Compared with the conventional process, which requires multiple temporary substrates to be set for multiple flipping of the epitaxial wafer, processing and separation of micro LED chip particles, the manufacturing process is simplified. At the same time, the use of bonding avoids the damage to the chip film caused by the peeling process due to the uneven bonding interface in the traditional bonding process. The embodiment of the present invention improves the reliability of the thin film chip structure.

[0069] The vertical structure Micro LED chip of the above embodiment of the present invention uses a double-sided alignment method to prepare electrodes and contact layers on the epitaxial wafer and perform segmentation, so that the Micro LED chip array is located on the substrate and the chip particles are peeled off. The above double-sided alignment method is used to ensure that the two surfaces of the epitaxial wafer are precisely aligned with micro-nano dimensions, and high-precision electrodes are prepared to ensure the precise alignment and electrical connection of each LED unit, thereby improving the uniformity and performance of the overall array.

[0070] Referring to FIG. 3 , a method for manufacturing a micro LED chip according to another embodiment of the present application is different from that in Embodiment 1 in that the chip segmentation step is performed after the first substrate is peeled off, and the light emitting surface of the micro LED chip is different from that in Embodiment 1.

[0071] The specific steps include:

[0072] Step S1, growing an epitaxial wafer structure on a first substrate; the epitaxial wafer structure includes sequentially growing a buffer layer 101, a barrier layer / sacrificial layer 102, an ohmic contact layer 103, an n-type confinement layer 104, an MQW active layer 105, a p-type confinement layer 106 and a p-type ohmic contact window layer.

[0073] Step S2, such as Figure 3a A patterned ohmic contact layer and a first electrode layer 201 are fabricated in the direction of the epitaxial wafer structure away from the first substrate, and the first electrode layer 201 is located on the ohmic contact layer.

[0074] The selection of materials and working principles involved in the specific operations of steps S1 and S2 are the same as those of steps S1 and S2 in the previous embodiment, and will not be described again here;

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

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

[0077] Step S4, using the second substrate as a temporary support substrate, etching the sacrificial layer or the substrate and the barrier layer to achieve substrate peeling of the first substrate;

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

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

[0080] Using photolithography technology, a graphic second electrode layer is formed. Each independent second electrode area in the pattern and the first electrode area corresponding to the vertical direction in step S2 together constitute two electrodes of the vertical micro LED chip. In order to ensure the above correspondence of the micron-sized micro LED chip, double-sided alignment lithography is used to ensure the precise alignment of the double-sided processing patterns of the epitaxial wafer. Specifically, an alignment mark method is used, and marking can be selected on the epitaxial wafer and the photolithography mask to achieve the above alignment. The marking method can be selected in the form of a cross, a square, a circle, etc. The size and position of the above two electrodes can be selected according to specific needs.

[0081] Step S6, as Figure 3d-3e As shown, the epitaxial wafer structure is vertically divided so that a number of Micro LED chips are arranged in an array on the second substrate, and a passivation protection layer is formed on the sidewalls and surface of the Micro LED chips to expose the electrode parts that need to be electrically connected;

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

[0083] Step S7, Figure 3f As shown, laser is used to act on the adhesive to peel the chip from the second substrate to produce microLED chip particles.

[0084] The specific peeling operation 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 describe a process for preparing a micro LED chip according to one embodiment of the present invention with reference to a specific example.

[0086] Step S1, using GaAs as a temporary substrate, a GaAs buffer layer, a sacrificial layer AlAs, an n-type AlGaInP ohmic contact layer 103, an n-type GaInP confinement layer 104, an MQW active layer 105, a p-type GaInP confinement layer 106 and a p-type GaP ohmic contact window layer 107 are grown by metal organic vapor chemical deposition (MOCVD) or molecular beam epitaxy (MBE) method.

[0087] Step S2, forming a patterned GaAs ohmic contact layer and a first Au electrode layer in a direction of the epitaxial wafer structure away from the first substrate, wherein the first electrode layer is located on the ohmic contact layer.

[0088] Step S3, vertically dividing the epitaxial wafer structure so that a plurality of Micro LED chips are arranged in an array on the first substrate, and forming a passivation protection layer on the sidewalls and surfaces of the Micro LED chips to expose the first electrode portion that needs to be electrically connected.

[0089] Specifically, dry or wet cutting is used, time and other conditions are controlled, and the epitaxial layer is cut 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 passivation protective layer is prepared on the side and upper surface of the micro LED by photolithography technology. The material of the protective layer 202 is one or more of SiO2, Al2O3, and Si3N4. The passivation protective layer wraps part of the electrode and exposes the part of the electrode that needs to be electrically connected.

[0090] Step S4, temporarily bonding the glass substrate coated with ultraviolet photosensitive adhesive to the electrode side of the epitaxial wafer structure.

[0091] In step S5, the glass substrate is used as a temporary supporting substrate, the barrier layer and the substrate are etched to realize the stripping of the GaAs substrate, and a plurality of Micro LED chips are arranged on the glass substrate in an array form.

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

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

[0094] A preparation process of a micro LED chip according to another embodiment of the present invention is described with reference to a specific example.

[0095] Step S1, using GaAs as a temporary substrate, a GaAs buffer layer, a sacrificial layer AlAs, an n-type AlGaInP ohmic contact layer 103, an n-type GaInP confinement layer 104, an MQW active layer 105, a p-type GaInP confinement layer 106 and a p-type GaP ohmic contact window layer 107 are grown by metal organic vapor chemical deposition (MOCVD) or molecular beam epitaxy (MBE) method.

[0096] Step S2, forming a patterned GaAs ohmic contact layer and a first Au electrode layer in a direction of the epitaxial wafer structure away from the GaAs substrate, wherein the first electrode layer is located on the ohmic contact layer.

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

[0098] In step S4, the glass substrate is used as a temporary supporting substrate, the barrier layer and the substrate are etched to realize the stripping of the GaAs substrate, and a plurality of Micro LED chips are arranged on the glass substrate in an array form.

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

[0100] Step S6, vertically dividing the epitaxial wafer structure so that a plurality of Micro LED chips are arranged in an array on a glass substrate, and a passivation protection layer is formed on the sidewalls and surface of the Micro LED chips to expose the second electrode portion that needs to be electrically connected.

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

[0102] The above description of the exemplary embodiments of the present disclosure is presented only for the purpose of illustration and description, and is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. In accordance with the above teachings, many modifications and variations are possible. The embodiments are selected and described to explain the principles of the present disclosure and its practical application, so that other technical personnel in the field can utilize the present disclosure and various embodiments, and have various modifications suitable for the specific purposes contemplated. Without departing from the spirit and scope of the present disclosure, replacement embodiments will become apparent to those skilled in the art to which the present disclosure belongs. Therefore, the scope of the present disclosure is limited by the appended claims rather than by the foregoing description and the exemplary embodiments described therein.

Claims

1. A method for manufacturing a micro LED chip, comprising: S1, growing an epitaxial wafer structure on a first substrate; the epitaxial wafer structure includes sequentially growing a buffer layer, a barrier layer / sacrificial layer, an n-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; S2, forming a patterned p-ohmic contact layer and a first electrode layer in the direction of the epitaxial wafer structure away from the first substrate, wherein the first electrode layer is located on the p-ohmic contact layer; S3, vertically dividing the epitaxial wafer structure so that a plurality of Micro LED chips are arranged on the first substrate in an array form; 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 supporting substrate, etching the sacrificial layer or etching the substrate and the barrier layer to peel off the first substrate, and placing a plurality of Micro LED chips in an array on the second substrate; S6, using the second substrate as a temporary support, forming a patterned second electrode layer in a direction of the epitaxial structure away from the second substrate; S7 uses laser to act on adhesive to peel the chip from the second substrate to make micro LED chips.

2. The method according to claim 1, wherein: In the step S3, the epitaxial wafer is vertically divided into the barrier layer / sacrificial layer, the buffer layer, and the upper surface of the first substrate.

3. The method according to claim 1, wherein: After the epitaxial wafer structure is vertically divided in the S3 step, a passivation protection layer is formed on the sidewalls and the upper surface of the Micro LED chip to expose the first electrode portion that needs to be electrically connected.

4. The method according to claim 1, wherein: After the second electrode layer is formed in step S6, the adhesive layer between the micro LEDs is vertically divided.

5. The method according to claim 5, wherein: The vertical separation of the adhesive layer is done by a combination of laser decomposition and dry etching.

6. According to the manufacturing method of claim 1, the adhesive is a UV adhesive, and a laser with a wavelength of 248nm is used to decompose the adhesive in the direction perpendicular to the electrode so that the decomposition is complete, and a laser with a wavelength of 355nm is used to decompose the remaining adhesive to achieve the separation of the micro LED and the second substrate.

7. A method for manufacturing a micro LED chip, comprising: S1, growing an epitaxial wafer structure on a first substrate; the epitaxial wafer structure includes sequentially growing a buffer layer, a barrier layer / 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; S2, forming a patterned p-ohmic contact layer and a first electrode layer in the direction of the epitaxial wafer structure away from the first substrate, wherein the first electrode layer is located on the p-ohmic 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 supporting substrate, etching the sacrificial layer or etching the substrate and the barrier layer to realize substrate peeling of the first substrate; S5, forming a patterned second electrode layer in a direction of the epitaxial wafer structure away from the second substrate; S6, vertically dividing the epitaxial wafer structure so that a plurality of Micro LED chips are arranged on the second substrate in an array form; S7 uses laser to act on adhesive to peel the chip from the second substrate to make micro LED chips.

8. The method according to claim 7, wherein: In the step S6, the epitaxial wafer is vertically divided to the surface of the bonding layer facing away from the second substrate or to the upper surface of the second substrate.

9. The method according to claim 7, wherein: After the epitaxial wafer structure is vertically divided in step S6, a passivation protection layer is formed on the sidewalls and upper surface of the Micro LED chip to expose the second electrode portion that needs to be electrically connected.

10. The method according to any one of the preceding items, wherein: The electrode layer of each micro LED chip is prepared by double-sided alignment lithography.

11. The method according to any one of the preceding claims, wherein: The adhesive is a polymer adhesive that can be decomposed by laser, preferably an ultraviolet photosensitive adhesive.

12. According to any of the above-mentioned production methods, the thickness of the adhesive layer is 2.5-5 um.

13. A micro LED chip manufactured by any of the aforementioned manufacturing methods.

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