LED chip assembly, manufacturing method thereof and LED chip stripping method

Abstract

The invention relates to an LED chip assembly, a manufacturing method thereof and an LED chip stripping method. The manufacturing method of the LED chip assembly comprises the steps that an epitaxial wafer is provided, the epitaxial wafer comprises a substrate, a sacrificial layer and a functional layer, the sacrificial layer and the functional layer are sequentially stacked on the substrate, and the sacrificial layer can be decomposed by illumination; patterning the functional layer so as to form a plurality of LED epitaxial structures on the substrate, and enabling channels between adjacent LED epitaxial structures to be exposed out of the sacrificial layer; and depositing a passivation layer on the epitaxial wafer to enable the passivation layer to at least cover the LED epitaxial structure, an electrode hole is formed in the passivation layer, and an electrode is evaporated in the electrode hole, so that the electrode is connected with the LED epitaxial structure. According to the scheme, passivation layer chippings generated by stripping and falling of the MicroLED during laser stripping of the MicroLED can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of LED chips, and in particular to an LED chip assembly and a manufacturing method thereof, and an LED chip stripping method. Background Art

[0002] Micro LED refers to Micro LED or Mini LED. Compared with traditional LED, its size is reduced from millimeter level to micro-nano level. When it is integrated into a high-density, small-size array and used in the display field, it has the advantages of high brightness, high resolution, high contrast, low energy consumption, and long service life. At the same time, it also has excellent performance in response speed and thermal stability.

[0003] To make a MicroLED array, it is first necessary to grow semiconductor materials on substrates such as sapphire, single-crystal gallium nitride, silicon carbide, and gallium arsenide, and form independent light-emitting units through semiconductor processes, and then peel the independent light-emitting units from the substrate and transfer them to a suitable transfer substrate. Among them, the main ways to peel the light-emitting units from the substrate are chemical peeling, mechanical peeling, thermal peeling, and laser peeling. Laser peeling technology mainly uses the different absorption of lasers by semiconductor materials and substrates, and the characteristics that some semiconductor materials can decompose after absorbing lasers to achieve the purpose of peeling. Compared with other methods, laser peeling technology has the characteristics of high efficiency, no pollution, less device damage, and high yield, so it can better meet the requirements of industrial production.

[0004] However, in the process of peeling the MicroLED from the substrate, it is often encountered that there are passivation layer debris after the MicroLED is peeled off, which affects the yield of subsequent processes. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide an LED chip assembly and a method for manufacturing the same, as well as an LED chip peeling method, in order to solve the problem that during MicroLED laser peeling, there are passivation layer debris after MicroLED peeling, which affects the yield of subsequent processes.

[0006] In a first aspect, the present application provides a method for manufacturing an LED chip assembly, comprising:

[0007] Providing an epitaxial wafer, the epitaxial wafer comprising a substrate, and a sacrificial layer and a functional layer sequentially stacked on the substrate, wherein the sacrificial layer can be decomposed by light;

[0008] Patterning the functional layer to form a plurality of LED epitaxial structures on the substrate, and allowing the channels between adjacent LED epitaxial structures to expose the sacrificial layer; and

[0009] Depositing a passivation layer on the epitaxial wafer so that the passivation layer at least covers the LED epitaxial structure;

[0010] An electrode hole is opened on the passivation layer, and an electrode is evaporated in the electrode hole to connect the electrode to the LED epitaxial structure.

[0011] In the embodiment of the present application, when a plurality of LED epitaxial structures are formed in the patterned functional layer (i.e., the main layer structure constituting the LED epitaxy, including at least an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer), the sacrificial layer on the channel between adjacent LED epitaxial structures is retained so that when the LED chip in the LED chip assembly is subsequently peeled off, the sacrificial layer on the channel between adjacent LED epitaxial structures is decomposed so that at least part of the passivation layer is suspended between the substrate; thereby ensuring that when the LED chip is separated from the substrate, the passivation layer on the LED chip and the substrate are broken by shear force; overcoming the problem of the traditional method in which the passivation layer is directly connected to the substrate, and when the LED chip is separated from the substrate, the passivation layer is separated from the substrate by pulling force, resulting in the occurrence of passivation layer debris.

[0012] In an optional embodiment, after patterning the functional layer, the method further comprises:

[0013] The sacrificial layer exposed by the channel is thinned so that the thickness of the sacrificial layer exposed by the channel is 0.1-2 um.

[0014] In an embodiment of the present application, if the thickness of the sacrificial layer exposed by the channel is greater than a certain threshold, when the LED chip is peeled off, after the sacrificial layer connected to the substrate is photodecomposed, the LED chip is still connected to the thicker sacrificial layer on the channel and is difficult to detach from the substrate. Therefore, in an embodiment of the present application, it is necessary to control the thickness of the sacrificial layer exposed by the channel to improve the efficiency of LED chip peeling. The present application has concluded through a large amount of experimental experience that maintaining the thickness of the sacrificial layer on the channel at 0.1-2um can effectively improve the efficiency of LED chip peeling.

[0015] In an optional implementation, the passivation layer only covers the surface of the LED epitaxial structure.

[0016] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel between adjacent LED epitaxial structures can be removed by etching so that the passivation layer only covers the surface of the LED epitaxial structure. In this way, only the sacrificial layer is connected to the substrate on the channel, and the passivation layer will not be affected when the LED chip is peeled off. It is understandable that the passivation layer on the channel can also be removed by other methods, and the embodiment of the present application does not limit the removal method.

[0017] In an optional implementation, the passivation layer covers the surface of the LED epitaxial structure and the sacrificial layer exposed on the channel.

[0018] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel is not processed. When the LED chip is peeled off, the part of the sacrificial layer close to the LED chip on the channel can be decomposed to make the passivation layer and the substrate suspended. In this way, when the LED chip is separated from the substrate, the passivation layer can be broken by shear force, thereby reducing the probability of debris in the passivation layer. In addition, in the present embodiment, after the passivation layer is deposited, the passivation layer on the channel is not processed, which can reduce a process, thereby reducing the manufacturing cost.

[0019] In an optional embodiment, the material of the sacrificial layer includes one or more of gallium nitride, BCB glue, and silicon carbide.

[0020] In a second aspect, based on the same inventive concept, the present application also provides an LED chip assembly, comprising:

[0021] substrate;

[0022] a sacrificial layer stacked on the substrate;

[0023] A plurality of LED epitaxial structures are arranged on the sacrificial layer at intervals;

[0024] The surface of each LED epitaxial structure is covered with a passivation layer;

[0025] The passivation layer is provided with an electrode hole, an electrode is provided in the electrode hole, and the electrode is connected to the LED epitaxial structure.

[0026] In the embodiment of the present application, a sacrificial layer is provided on the channel between adjacent LED epitaxial structures, so that when the LED chip in the LED chip assembly is subsequently peeled off, the sacrificial layer on the channel between adjacent LED epitaxial structures is decomposed, so that at least part of the passivation layer is suspended between the substrate; thereby ensuring that when the LED chip is separated from the substrate, the passivation layer on the LED chip and the substrate are broken by shear force; overcoming the problem of the traditional method in which the passivation layer is directly connected to the substrate, and when the LED chip is separated from the substrate, the passivation layer is separated from the substrate by pulling force, resulting in the appearance of passivation layer debris.

[0027] In an optional implementation, the thickness of the sacrificial layer on the channel between adjacent LED epitaxial structures is 0.1-2 um.

[0028] In an embodiment of the present application, if the thickness of the sacrificial layer exposed by the channel is greater than a certain threshold, when the LED chip is peeled off, after the sacrificial layer connected to the substrate is photodecomposed, the LED chip is still connected to the thicker sacrificial layer on the channel and is difficult to detach from the substrate. Therefore, in an embodiment of the present application, it is necessary to control the thickness of the sacrificial layer exposed by the channel to improve the efficiency of LED chip peeling. The present application has concluded through a large amount of experimental experience that maintaining the thickness of the sacrificial layer on the channel at 0.1-2um can effectively improve the efficiency of LED chip peeling.

[0029] In an optional implementation, the passivation layer also covers the sacrificial layer on the channel.

[0030] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel is not processed. When the LED chip is peeled off, the part of the sacrificial layer close to the LED chip on the channel can be decomposed to make the passivation layer and the substrate suspended. In this way, when the LED chip is separated from the substrate, the passivation layer can be broken by shear force, thereby reducing the probability of debris in the passivation layer. In addition, in the present embodiment, after the passivation layer is deposited, the passivation layer on the channel is not processed, which can reduce a process, thereby reducing the manufacturing cost.

[0031] In an optional embodiment, the material of the sacrificial layer includes one or more of gallium nitride, BCB glue, and silicon carbide.

[0032] In a third aspect, based on the same inventive concept, the present application also provides a method for stripping an LED chip, comprising:

[0033] Provide an LED chip assembly as described in the first aspect or the second aspect, wherein the LED epitaxial structure of the LED chip assembly, the passivation layer on the LED epitaxial structure, and the electrode connected to the LED epitaxial structure constitute the LED chip;

[0034] providing a substrate;

[0035] The LED chip assembly is arranged corresponding to the substrate;

[0036] Using laser to irradiate the sacrificial layer, the sacrificial layer is decomposed, so that the irradiated LED chip on the LED chip assembly is transferred to the substrate;

[0037] The light spot area is larger than the area projected by the LED chip on the sacrificial layer, and the light spot area is the area covered by the light spot irradiated by the laser on the sacrificial layer.

[0038] In the embodiment of the present application, the sacrificial layer on the channel between the adjacent LED epitaxial structures is retained. When laser stripping the LED chip in the LED chip assembly, the irradiation area of ​​the laser spot is made larger than the projection area of ​​the LED chip on the sacrificial layer, so that at least part of the sacrificial layer on the channel between the adjacent LED epitaxial structures can be decomposed, so that at least part of the passivation layer is suspended between the substrate; thereby ensuring that when the LED chip is separated from the substrate, the passivation layer on the LED chip and the substrate are broken by shear force. The probability of passivation layer debris appearing during laser stripping of the LED chip can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the structure of a traditional laser stripping LED chip;

[0040] Figure 2 A schematic diagram of a process for manufacturing an LED chip assembly provided in an embodiment of the present application;

[0041] Figure 3 A schematic diagram of the structure of the functional layer patterning process in the LED chip assembly manufacturing method provided in an embodiment of the present application;

[0042] Figure 4 A schematic diagram of the structure after the sacrificial layer is thinned in the LED chip assembly manufacturing method provided in an embodiment of the present application;

[0043] Figure 5 A schematic diagram of the structure after depositing a passivation layer in a method for manufacturing an LED chip assembly provided in an embodiment of the present application;

[0044] Figure 6 A schematic diagram of the structure after depositing a passivation layer in another method for manufacturing an LED chip assembly provided in an embodiment of the present application;

[0045] Figure 7 A schematic diagram of the structure of an LED chip assembly provided in an embodiment of the present application;

[0046] Figure 8 Another schematic diagram of the structure of an LED chip assembly provided in the embodiment of the present application

[0047] Fig. 9 A schematic diagram of another LED chip assembly structure provided in the embodiment of the present application

[0048] Fig.10 A schematic diagram of a process for peeling an LED chip provided in this application;

[0049] Fig.11 A schematic diagram of the process structure of an LED chip peeling method provided in an embodiment of the present application.

[0050] Description of reference numerals:

[0051] 10-substrate; 20-functional layer; 21-LED epitaxial structure; 30-passivation layer; 31-passivation layer debris; 40-electrode; 50-sacrificial layer; 60-substrate. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0053] The disclosure of the present invention provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described in the present invention. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. Generally, the terms can be understood at least in part according to the usage of the present invention. For example, the term "one or more" used in the present invention depends at least in part on the present invention and can be used to describe any component, structure or feature in a singular form, or can be used to describe a combination of components, structures or features in a plural form. Similarly, terms such as "one", "an" or "the" can also be understood at least in part to convey singular usage or convey plural usage depending on the present invention. In addition, the term "based on..." can be understood as not necessarily intended to convey a set of exclusive factors, but at least in part depending on the present invention can instead allow the presence of additional factors that do not necessarily have to be explicitly described.

[0055] It should be easily understood that the meanings of “on,” “over,” and “on…” in the present invention should be interpreted in the broadest manner, so that “on…” means not only “directly on something,” but also means “on something” including the presence of intermediate components or layers therebetween, and “on something” or “on something” means not only “on something” or “on something,” but also includes the meaning of “on something” or “on something” without any intermediate components or layers therebetween.

[0056] Additionally, for ease of description, spatially relative terms such as "below," "beneath," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or component to another element or component as shown in the drawings. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the drawings. The device may be otherwise oriented, rotated 90 degrees or at other orientations, and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0057] The term "layer" used in the present invention refers to a material portion including an area with a certain thickness. The layer can extend over the entire lower or upper structure, or can have a degree less than the scope of the lower or upper structure. In addition, the layer can be a region of a homogeneous or inhomogeneous continuous structure, and its thickness is less than the thickness of the continuous structure. For example, the layer can be located between the top surface and the bottom surface of the continuous structure or between any pair of horizontal planes therebetween. The layer can extend horizontally, vertically and / or along a tapered surface. The substrate can be a layer, one or more layers can be included therein, and / or one or more layers can be provided thereon, above and / or below. A layer can include multiple layers. For example, the semiconductor layer can include one or more doped or undoped semiconductor layers, and can have the same or different materials.

[0058] refer to Figure 1, is a schematic diagram of a conventional laser stripping LED chip. As shown in the figure, the LED chip includes an LED epitaxial structure 21, a passivation layer 30 and an electrode 40; the LED chip is arranged on a substrate. When manufacturing the LED chip, in order to make the passivation layer completely cover the side wall of the LED chip and the accuracy of the etching equipment, the passivation layer on the channel is partially etched after the passivation layer is deposited, so that the passivation layer on the channel near the LED side wall directly covers the substrate. When the LED chip is laser stripped, the laser decomposes the gallium nitride (sacrificial layer) on the contact surface between the LED epitaxial structure and the substrate, and then generates an impact force on the LED chip, so that the LED chip is separated from the substrate. In this process, since the passivation layer on the channel near the LED side wall directly covers the substrate, a pulling force is generated between the passivation layer on the LED chip and the passivation layer covering the substrate, resulting in partial fragmentation of the passivation layer to generate passivation layer debris 31. The falling of the passivation layer debris 31 will affect the yield of the subsequent process. In addition, due to the influence of the pulling force between the passivation layer around the side wall of the LED chip and the substrate, the LED chip may also break.

[0059] Based on this, the present application hopes to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in the subsequent embodiments.

[0060] refer to Figure 2 , is a schematic flow chart of a method for manufacturing an LED chip assembly provided in an embodiment of the present application, the method comprising:

[0061] 101: Provide an epitaxial wafer, wherein the epitaxial wafer comprises a substrate, and a sacrificial layer and a functional layer sequentially stacked on the substrate, wherein the sacrificial layer can be decomposed by light.

[0062] In an embodiment of the present application, the above-mentioned functional layer constitutes the main epitaxial layer structure of the LED, and the above-mentioned functional layer may include an active layer of a first semiconductor layer and a second semiconductor layer stacked sequentially on the above-mentioned sacrificial layer, wherein the first semiconductor layer and the second semiconductor layer are doped semiconductor layers of different types.

[0063] The first semiconductor layer may be an N-doped semiconductor layer or a P-doped semiconductor layer, and the second semiconductor layer may be a P-doped semiconductor layer or an N-doped semiconductor layer. The active layer may be a multiple quantum well structure (Multiple Quantum Well, MQW). Specifically, the semiconductor layer may be a III-V compound semiconductor material such as GaN, AlGaN, InGaN, AlInP, GaInP, AlGaInP, etc.; the quantum well or quantum layer may be InGaN, AlGaN, InN, InAlN, AlInGaN, etc., and the quantum barrier alternately stacked with the quantum well layer may be GaN, AlN, AlGaN, AlInGaN, InAlN, etc.; the multiple quantum well structure may include one or two or three or four or five or six or six or seven or eight quantum wells (or at least one quantum hole); the wavelength emitted by the active layer may be a wavelength in the blue light band, a wavelength in the green light band, or a wavelength in the red light band, which is not specifically limited in the embodiments of the present application.

[0064] In an embodiment of the present application, the sacrificial layer is made of a material that can be decomposed by light, thereby separating the functional layer from the substrate; for example, the material of the sacrificial layer includes one or more of gallium nitride, BCB glue, ultraviolet glue, silicon carbide, etc.

[0065] In an embodiment of the present application, the substrate may be a growth substrate or a temporary substrate. For example, the epitaxial wafer may be a GaN-based blue-green light epitaxial wafer, the substrate may be a growth substrate sapphire, the sacrificial layer may be U-type GaN, and the functional layer may include an N-type GaN layer, an active layer, and a P-type GaN layer stacked in sequence. For another example, the epitaxial wafer may be a red light epitaxial wafer of a phosphoindium gallium aluminum system, the substrate may be a temporary substrate sapphire, the sacrificial layer may be BCB glue or GaN or silicon carbide, etc., and the functional layer may include a P-type AlInP (or AlGaInP) layer, an active layer, and an N-type AlInP (or AlGaInP) layer stacked in sequence. It is understandable that, regardless of whether the functional layer corresponds to blue-green light or red light, the substrate may be a temporary substrate, and the present application does not limit this.

[0066] 102: Patterning the functional layer to form a plurality of LED epitaxial structures on the substrate, and allowing the channels between adjacent LED epitaxial structures to expose the sacrificial layer.

[0067] The above patterning refers to forming a predetermined pattern shape of the layer structure through multiple processes such as photolithography and etching. After the above patterning of the functional layer 20, a plurality of independent LED epitaxial structures 21 are formed, each LED epitaxial structure 21 is separated from each other, and the original functional layer between adjacent LED epitaxial structures 21 is removed to form a channel, and the sacrificial layer 50 is exposed on the channel, such as Figure 3 shown.

[0068] The layer structure of the LED epitaxial structure is the same as the functional layer, and both include the main epitaxial layer structure of the LED: an active layer of the first semiconductor layer and a second semiconductor layer.

[0069] In an optional implementation, after patterning the functional layer, the method further comprises: thinning the sacrificial layer exposed by the channel, so that the thickness of the sacrificial layer exposed by the channel is 0.1-2 um.

[0070] In the embodiment of the present application, the thickness of the sacrificial layer on the channel between adjacent LED epitaxial structures after thinning can be 0.1-0.3um, 0.3-0.5um, 0.5-1um, 1-2um, 0.2-2um or 2-2.5um.

[0071] It is understandable that the above-mentioned thinning of the sacrificial layer can be performed simultaneously with part of the process of patterning the functional layer, or can be performed separately after the functional layer patterning is completed. For example, the sacrificial layer can be etched simultaneously with the etching of the above-mentioned channel when the functional layer is patterned. The schematic diagram of the structure after thinning the sacrificial layer on the channel can be referred to Figure 4 .

[0072] In an embodiment of the present application, if the thickness of the sacrificial layer exposed by the channel is greater than a certain threshold, when the LED chip is peeled off, after the sacrificial layer connected to the substrate is photodecomposed, the LED chip is still connected to the thicker sacrificial layer on the channel and is difficult to detach from the substrate. Therefore, in an embodiment of the present application, it is necessary to control the thickness of the sacrificial layer exposed by the channel to improve the efficiency of LED chip peeling. The present application has concluded through a large amount of experimental experience that maintaining the thickness of the sacrificial layer on the channel at 0.1-2um can effectively improve the efficiency of LED chip peeling.

[0073] 103: Depositing a passivation layer on the epitaxial wafer, so that the passivation layer at least covers the LED epitaxial structure.

[0074] In the embodiment of the present application, the passivation layer covers the surface of the LED epitaxial structure to protect the LED epitaxial structure. The passivation layer can be one or more of Al2O3, AlN, SiN, SiO2, and AlON thin films.

[0075] In an optional embodiment, the passivation layer covers the surface of the LED epitaxial structure and the sacrificial layer exposed on the channel, such as Figure 5 shown.

[0076] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel is not processed. When the LED chip is peeled off, the part of the sacrificial layer close to the LED chip on the channel can be decomposed to make the passivation layer and the substrate suspended. In this way, when the LED chip is separated from the substrate, the passivation layer can be broken by shear force, thereby reducing the probability of debris in the passivation layer. In addition, in the present embodiment, after the passivation layer is deposited, the passivation layer on the channel is not processed, which can reduce a process, thereby reducing the manufacturing cost.

[0077] In an optional embodiment, the passivation layer only covers the surface of the LED epitaxial structure. Figure 6 shown.

[0078] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel between adjacent LED epitaxial structures can be removed by etching so that the passivation layer only covers the surface of the LED epitaxial structure. In this way, only the sacrificial layer is connected to the substrate on the channel, and the passivation layer will not be affected when the LED chip is peeled off. It is understandable that the passivation layer on the channel can also be removed by other methods, and the embodiment of the present application does not limit the removal method.

[0079] 104: Opening electrode holes on the passivation layer, and evaporating electrodes in the electrode holes to connect the electrodes to the LED epitaxial structure, such as Figure 7-9 .

[0080] In the embodiment of the present application, the electrode 40 is one or more metals that can form ohmic contact with the LED epitaxial structure for current conduction. For example, the electrode 40 can be formed of a combination of one or more of Cr, Pt, Ti, Ni, Au, and Sn.

[0081] In the embodiment of the present application, when a plurality of LED epitaxial structures are formed in the patterned functional layer (i.e., the main layer structure constituting the LED epitaxy, including at least an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer), the sacrificial layer on the channel between adjacent LED epitaxial structures is retained so that when the LED chip in the LED chip assembly is subsequently peeled off, the sacrificial layer on the channel between adjacent LED epitaxial structures is decomposed so that at least part of the passivation layer is suspended between the substrate; thereby ensuring that when the LED chip is separated from the substrate, the passivation layer on the LED chip and the substrate are broken by shear force; overcoming the problem of the traditional method in which the passivation layer is directly connected to the substrate, and when the LED chip is separated from the substrate, the passivation layer is separated from the substrate by pulling force, resulting in the occurrence of passivation layer debris.

[0082] refer to Figure 7-9Based on the same inventive concept, the present application also provides an LED chip assembly, comprising: a substrate 10; a sacrificial layer 50 stacked on the substrate; a plurality of LED epitaxial structures 21 are arranged on the sacrificial layer at intervals; the surface of each of the LED epitaxial structures is covered with a passivation layer 30; an electrode hole is arranged on the passivation layer, an electrode 40 is arranged in the electrode hole, and the electrode is connected to the LED epitaxial structure.

[0083] In an embodiment of the present application, the layer structure of the LED epitaxial structure includes an active layer of a first semiconductor layer and a second semiconductor layer sequentially stacked on the sacrificial layer, wherein the first semiconductor layer and the second semiconductor layer are doped semiconductor layers of different types.

[0084] It is understandable that the above LED epitaxial structure may also include other layer structures, such as a current spreading layer, an ohmic contact layer, and the like.

[0085] The first semiconductor layer may be an N-doped semiconductor layer or a P-doped semiconductor layer, and the second semiconductor layer may be a P-doped semiconductor layer or an N-doped semiconductor layer. The active layer may be a multiple quantum well structure (Multiple Quantum Well, MQW). Specifically, the semiconductor layer may be a III-V compound semiconductor material such as GaN, AlGaN, InGaN, AlInP, GaInP, AlGaInP, etc.; the quantum well or quantum layer may be InGaN, AlGaN, InN, InAlN, AlInGaN, etc., and the quantum barrier alternately stacked with the quantum well layer may be GaN, AlN, AlGaN, AlInGaN, InAlN, etc.; the multiple quantum well structure may include one or two or three or four or five or six or six or seven or eight quantum wells (or at least one quantum hole); the wavelength emitted by the active layer may be a wavelength in the blue light band, a wavelength in the green light band, or a wavelength in the red light band, which is not specifically limited in the embodiments of the present application.

[0086] In an embodiment of the present application, the sacrificial layer is made of a material that can be decomposed by light, thereby separating the functional layer from the substrate; for example, the material of the sacrificial layer includes one or more of gallium nitride, BCB glue, ultraviolet glue, silicon carbide, etc.

[0087] In an embodiment of the present application, the substrate may be a growth substrate or a temporary substrate. For example, the epitaxial wafer may be a GaN-based blue-green light epitaxial wafer, the substrate may be a growth substrate sapphire, the sacrificial layer may be U-type GaN, and the functional layer may include an N-type GaN layer, an active layer, and a P-type GaN layer stacked in sequence. For another example, the epitaxial wafer may be a red light epitaxial wafer of a phosphoindium gallium aluminum system, the substrate may be a temporary substrate sapphire, the sacrificial layer may be BCB glue or GaN or silicon carbide, etc., and the functional layer may include a P-type AlInP (or AlGaInP) layer, an active layer, and an N-type AlInP (or AlGaInP) layer stacked in sequence. It is understandable that, regardless of whether the functional layer corresponds to blue-green light or red light, the substrate may be a temporary substrate, and the present application does not limit this.

[0088] In the embodiment of the present application, the passivation layer covers the surface of the LED epitaxial structure to protect the LED epitaxial structure. The passivation layer can be one or more of Al2O3, AlN, SiN, SiO2, and AlON thin films.

[0089] In the embodiment of the present application, by retaining the sacrificial layer on the channel between adjacent LED epitaxial structures, when the LED chip in the LED chip assembly is subsequently peeled off, the sacrificial layer on the channel between adjacent LED epitaxial structures is decomposed, so that at least part of the passivation layer is suspended between the substrate; thereby ensuring that when the LED chip is separated from the substrate, the passivation layer on the LED chip and the substrate are broken by shear force; overcoming the problem of the traditional method in which the passivation layer is directly connected to the substrate, and when the LED chip is separated from the substrate, the passivation layer is separated from the substrate by pulling force, resulting in the appearance of passivation layer debris.

[0090] In an optional embodiment, if Fig. 9 As shown, the thickness of the sacrificial layer on the channel between adjacent LED epitaxial structures is set to 0.1-2 um.

[0091] In the embodiment of the present application, the thickness of the sacrificial layer on the channel between adjacent LED epitaxial structures may be 0.1-0.3 um, 0.3-0.5 um, 0.5-1 um or 1-2 um.

[0092] In an embodiment of the present application, if the thickness of the sacrificial layer exposed by the channel is greater than a certain threshold, when the LED chip is peeled off, after the sacrificial layer connected to the substrate is photodecomposed, the LED chip is still connected to the thicker sacrificial layer on the channel and is difficult to detach from the substrate. Therefore, in an embodiment of the present application, it is necessary to control the thickness of the sacrificial layer exposed by the channel to improve the efficiency of LED chip peeling. The present application has concluded through a large amount of experimental experience that maintaining the thickness of the sacrificial layer on the channel at 0.1-2um can effectively improve the efficiency of LED chip peeling.

[0093] In an optional embodiment, if Figure 7 As shown, the passivation layer covers the surface of the LED epitaxial structure and the sacrificial layer on the channel.

[0094] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel is not processed. When the LED chip is peeled off, the part of the sacrificial layer close to the LED chip on the channel can be decomposed to make the passivation layer and the substrate suspended. In this way, when the LED chip is separated from the substrate, the passivation layer can be broken by shear force, thereby reducing the probability of debris in the passivation layer. In addition, in the present embodiment, after the passivation layer is deposited, the passivation layer on the channel is not processed, which can reduce a process, thereby reducing the manufacturing cost.

[0095] In an optional embodiment, if Figure 8 As shown, the passivation layer only covers the surface of the LED epitaxial structure.

[0096] In the embodiment of the present application, after the passivation layer is deposited, the passivation layer on the channel between adjacent LED epitaxial structures can be removed by etching so that the passivation layer only covers the surface of the LED epitaxial structure. In this way, only the sacrificial layer is connected to the substrate on the channel, and the passivation layer will not be affected when the LED chip is peeled off. It is understandable that the passivation layer on the channel can also be removed by other methods, and the embodiment of the present application does not limit the removal method.

[0097] refer to Fig.10 , is a schematic flow chart of a LED chip peeling method provided in the present application, the method comprising:

[0098] 201: Provide LED chip components.

[0099] In an embodiment of the present application, the above-mentioned LED chip assembly is the LED chip assembly described in any of the preceding embodiments; wherein, the LED epitaxial structure of the LED chip assembly, the passivation layer on the LED epitaxial structure, and the electrode connected to the LED epitaxial structure constitute the LED chip.

[0100] 202: Provide a substrate.

[0101] In an embodiment of the present application, the substrate includes a temporary substrate or a driving backplane.

[0102] 203: Arrange the LED chip assembly corresponding to the substrate.

[0103] 204: Using laser to irradiate the sacrificial layer, the sacrificial layer is decomposed, so that the irradiated LED chip on the LED chip assembly is transferred to the substrate.

[0104] The light spot area is larger than the area projected by the LED chip on the sacrificial layer, and the light spot area is the area covered by the light spot irradiated by the laser on the sacrificial layer.

[0105] In the embodiment of the present application, the sacrificial layer on the channel between the adjacent LED epitaxial structures is retained. When laser stripping the LED chip in the LED chip assembly, the irradiation area of ​​the laser spot is made larger than the projection area of ​​the LED chip on the sacrificial layer, so that at least part of the sacrificial layer on the channel between the adjacent LED epitaxial structures can be decomposed, so that at least part of the passivation layer is suspended between the substrate; thereby ensuring that when the LED chip is separated from the substrate, the passivation layer on the LED chip and the substrate are broken by shear force. The probability of passivation layer debris appearing when laser stripping the LED chip can be effectively reduced.

[0106] In an optional embodiment, before the sacrificial layer is irradiated with a laser and decomposed, so that the irradiated LED chip on the LED chip assembly is transferred to the substrate, the method further includes: irradiating the sacrificial layer adjacent to the LED chip on the channel with a laser, so that the sacrificial layer adjacent to the LED chip on the channel is at least partially decomposed. This ensures that when the subsequent step of "irradiating the sacrificial layer with a laser and decomposing the sacrificial layer so that the irradiated LED chip on the LED chip assembly is transferred to the substrate" is performed, the sacrificial layer adjacent to the LED chip on the channel is suspended from the substrate, so that the passivation layer and / or the sacrificial layer are broken by shear force when the LED chip is detached.

[0107] refer to Fig.11 , is a schematic diagram of the process structure of an LED chip stripping method provided in an embodiment of the present application; as shown in the figure, first provide the LED chip assembly and a substrate described in the aforementioned embodiment; then set the substrate and the LED chip assembly and the substrate relatively; then irradiate the sacrificial layer (taking U-type GaN as an example) at the corresponding position of the LED chip to be stripped by laser; wherein the area of ​​the laser spot irradiating the sacrificial layer is larger than the area of ​​the LED chip projected on the sacrificial layer; after being irradiated by the laser, the sacrificial layer decomposes N2 and metal Ga, and under the impact force of the generated N2, the LED chip is separated from the substrate and transferred to the substrate. wherein, since a sacrificial layer is provided on the channel between adjacent LED chips on the LED chip assembly, and the area of ​​the laser spot irradiating the sacrificial layer during laser stripping is larger than the area of ​​the LED chip projected on the sacrificial layer, when the LED chip is separated from the substrate, the sacrificial layer and / or the passivation layer adjacent to the LED chip to be stripped on the channel are subjected to shear force and broken. therefore, the generation of passivation layer debris caused by LED chip stripping can be effectively reduced.

[0108] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for manufacturing an LED chip assembly, characterized in that: include: Providing an epitaxial wafer, the epitaxial wafer comprising a substrate, and a sacrificial layer and a functional layer sequentially stacked on the substrate; Patterning the functional layer to form a plurality of LED epitaxial structures on the substrate, and making the channels between adjacent LED epitaxial structures expose the sacrificial layer; as well as Depositing a passivation layer on the epitaxial wafer so that the passivation layer at least covers the LED epitaxial structure; An electrode hole is opened on the passivation layer, and an electrode is evaporated in the electrode hole to connect the electrode to the LED epitaxial structure.

2. The method for manufacturing an LED chip assembly according to claim 1, wherein: After patterning the functional layer, the method further comprises: The sacrificial layer exposed by the channel is thinned so that the thickness of the sacrificial layer exposed by the channel is 0.1-2 um.

3. The method for manufacturing an LED chip assembly according to claim 1, wherein: The passivation layer only covers the surface of the LED epitaxial structure.

4. The method for manufacturing an LED chip assembly according to claim 1, wherein: The passivation layer covers the surface of the LED epitaxial structure and the sacrificial layer exposed on the channel.

5. The method for manufacturing an LED chip assembly according to any one of claims 1 to 4, characterized in that: The material of the sacrificial layer includes one or more of gallium nitride, BCB glue, and silicon carbide.

6. An LED chip assembly, characterized in that: include: substrate; a sacrificial layer stacked on the substrate; A plurality of LED epitaxial structures are arranged on the sacrificial layer at intervals; The surface of each LED epitaxial structure is covered with a passivation layer; The passivation layer is provided with an electrode hole, an electrode is provided in the electrode hole, and the electrode is connected to the LED epitaxial structure.

7. The LED chip assembly according to claim 6, characterized in that: The thickness of the sacrificial layer on the channel between adjacent LED epitaxial structures is 0.1-2 um.

8. The LED chip assembly according to claim 7, characterized in that: The passivation layer also covers the sacrificial layer on the channel.

9. The LED chip assembly according to any one of claims 6 to 8, characterized in that: The material of the sacrificial layer includes one or more of gallium nitride, BCB glue, and silicon carbide.

10. A method for stripping an LED chip, characterized in that: include: Providing an LED chip assembly as described in any one of claims 6 to 8; providing a substrate; The LED chip assembly is arranged corresponding to the substrate; Using laser to irradiate the sacrificial layer, the sacrificial layer is decomposed, so that the irradiated LED chip on the LED chip assembly is transferred to the substrate; The light spot area is larger than the area projected by the LED chip on the sacrificial layer, and the light spot area is the area covered by the light spot irradiated by the laser on the sacrificial layer.

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