Inverted Mini-LED chip, preparation method thereof and lighting equipment

Abstract

The invention provides an inverted Mini-LED chip, a preparation method thereof and lighting equipment, and relates to the technical field of semiconductors. According to the flip Mini-LED chip, the first DBR layer wrapping the core particle structure is formed around the core particle structure, so that film layers such as an N-type semiconductor layer are protected, and the DE deep etching process can be removed in the process of preparing the core particle structure; therefore, the purposes of improving the luminous efficiency of the flip Mini-LED chip, reducing the size of the chip and prolonging the service life of the flip Mini-LED chip are achieved. And the first DBR layer exposes a part of the surface of the first bonding pad and a part of the surface of the second bonding pad, so that normal electric connection between the flip Mini-LED chip and an external assembly can be ensured, and the use of the flip Mini-LED chip is not influenced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a flip-chip Mini-LED chip, a preparation method thereof, and a lighting device. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor light-emitting device that uses the principle of semiconductor PN junction electroluminescence to convert electrical energy into light energy. It has the advantages of small size, low power consumption and long life. It is now widely used in various scene lighting, backlighting, car lights and other fields.

[0003] With the gradual development of LED, LED lighting has completely replaced traditional lighting sources; the next major development direction of LED is the display industry. Currently, Mini-LED has become the new favorite of major LED companies, and they are all actively deploying Mini-LED chips; current Mini-LED chips basically adopt a flip-chip structure.

[0004] In the prior art, due to the packaging method of the flip-chip Mini-LED chip, it is necessary to ensure that the N-type semiconductor layer is not exposed to the outside, so a DE (full name in English: Deep Etching) deep etching process must be performed to form a cutting path that penetrates the N-type semiconductor layer to ensure that the subsequent DBR and other film layers can protect the N-type semiconductor layer, which seriously restricts the effective light-emitting area of ​​the flip-chip Mini-LED chip. As mentioned above, the N-type semiconductor layer is protected by the DBR (full name in English: Distributed Bragg Reflector) and other film layers in the cutting path, resulting in a very large cutting window to be reserved, because if the MESA edge is cut, the existing detection means of the chip segment cannot detect 100%, and the packaging cannot be 100% screened out, but the risk of dead lights during use is very high. And when performing DE deep etching, it is necessary to use a relatively thick glue (glue thickness is more than 9μm), because the thermal effect of the glue causes unexpected deformation when the size is small, which seriously restricts the size of the flip-chip Mini-LED chip.

[0005] Therefore, how to optimize the structure of flip-chip Mini-LED chips to improve luminous efficiency, reduce chip size and increase service life is a technical problem that needs to be urgently solved by technicians in this field. Summary of the invention

[0006] In view of the above problems, the present application provides a flip-chip Mini-LED chip and a preparation method thereof, and a lighting device, so as to achieve the purpose of improving the luminous efficiency of the flip-chip Mini-LED chip, reducing the chip size, and increasing the service life. The specific scheme is as follows:

[0007] In a first aspect, the present application provides a flip-chip Mini-LED chip, the flip-chip Mini-LED chip comprising:

[0008] A core structure; the core structure comprises a substrate; an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer which are located on one side of the substrate and are stacked in sequence; and a first pad electrically connected to the N-type semiconductor layer, and a second pad electrically connected to the P-type semiconductor layer;

[0009] A first DBR layer is provided to wrap the core particle structure, wherein the first DBR layer exposes a portion of the surface of the first pad and a portion of the surface of the second pad.

[0010] Preferably, in the above-mentioned flip-chip Mini-LED chip, the first DBR layer is prepared based on the ALD process.

[0011] Preferably, in the above flip-chip Mini-LED chip, the first DBR layer includes a first film layer and a second film layer that are alternately arranged;

[0012] The refractive index of the first film layer is different from the refractive index of the second film layer.

[0013] Preferably, in the above flip-chip Mini-LED chip, the refractive index of the first film layer is in the range of 1.38-1.67;

[0014] The refractive index of the second film layer is in the range of 1.97-2.35.

[0015] Preferably, in the above flip-chip Mini-LED chip, the material of the first film layer is MgF2, SiO2 or Al2O3;

[0016] The material of the second film layer is ZrO2, HfO2, Ta2O5, ZnS or TiO2.

[0017] Preferably, in the above flip-chip Mini-LED chip, the first DBR layer also exposes a surface of the substrate facing away from the N-type semiconductor layer;

[0018] The flip-chip Mini-LED chip further includes:

[0019] A reflective layer is located on a side of the first DBR layer away from the core structure.

[0020] A second aspect of the present application provides a method for preparing a flip-chip Mini-LED chip, the method for preparing a flip-chip Mini-LED chip comprising:

[0021] providing a substrate;

[0022] Forming an N-type semiconductor layer, a multi-quantum well layer, and a P-type semiconductor layer stacked in sequence on one side of the substrate;

[0023] forming a first pad and a second pad, wherein the first pad is electrically connected to the N-type semiconductor layer, and the second pad is electrically connected to the P-type semiconductor layer;

[0024] Performing cutting processing to form multiple independent core particle structures;

[0025] A first DBR layer is formed, wherein the first DBR layer wraps the core particle structure, and the first DBR layer exposes a portion of the surface of the first pad and a portion of the surface of the second pad.

[0026] Preferably, in the above-mentioned method for preparing the flip-chip Mini-LED chip, the forming of the first DBR layer comprises:

[0027] The first DBR layer is formed based on an ALD process.

[0028] Preferably, in the above-mentioned method for preparing a flip-chip Mini-LED chip, the method for preparing a flip-chip Mini-LED chip further comprises:

[0029] forming a reflective layer on a side of the first DBR layer away from the core structure;

[0030] Part of the reflective layer and the first DBR layer is removed to expose a surface of the substrate facing away from the N-type semiconductor layer.

[0031] A third aspect of the present application provides a lighting device, comprising the flip-chip Mini-LED chip described in any one of the above items.

[0032] By means of the above technical solution, the present application provides a flip-chip Mini-LED chip and a preparation method and lighting equipment thereof. The flip-chip Mini-LED chip forms a first DBR layer around the core structure to wrap the core structure, thereby protecting the film layers such as the N-type semiconductor layer, so that the DE deep etching process can be removed during the preparation of the core structure, thereby achieving the purpose of improving the luminous efficiency of the flip-chip Mini-LED chip, reducing the chip size and increasing the service life. In addition, the first DBR layer exposes part of the surface of the first pad and part of the surface of the second pad, ensuring that the flip-chip Mini-LED chip can achieve normal electrical connection with the external components without affecting the use of the flip-chip Mini-LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0034] Figure 1 A schematic diagram of the structure of a flip-chip Mini-LED chip provided by an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of the structure of another flip-chip Mini-LED chip provided by an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of a process for preparing a flip-chip Mini-LED chip provided by an embodiment of the present invention;

[0037] Figure 4-Figure 5 for Figure 3 A schematic diagram of a part of the structure corresponding to the preparation method shown;

[0038] Figure 6 A schematic flow chart of another method for preparing a flip-chip Mini-LED chip provided by an embodiment of the present invention;

[0039] Figure 7-Figure 8 for Figure 6 Schematic diagram of the partial structure corresponding to the preparation method shown. DETAILED DESCRIPTION

[0040] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation mode of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation to the present application.

[0043] refer to Figure 1 , Figure 1 A schematic diagram of the structure of a flip-chip Mini-LED chip provided in an embodiment of the present invention. A flip-chip Mini-LED chip provided in an embodiment of the present invention includes:

[0044] A core structure; the core structure includes a substrate 11; an N-type semiconductor layer 12, a multi-quantum well layer 13 and a P-type semiconductor layer 14 located on one side of the substrate 11 and stacked in sequence; and a first pad 15 electrically connected to the N-type semiconductor layer 12, and a second pad 16 electrically connected to the P-type semiconductor layer 14.

[0045] The first DBR layer 17 wraps the core structure, and the first DBR layer 17 exposes a portion of the surface of the first pad 15 and a portion of the surface of the second pad 16 .

[0046] Specifically, in the embodiment of the present invention, the substrate 11 includes but is not limited to a sapphire substrate, the N-type semiconductor layer 12 includes but is not limited to an N-type gallium nitride layer, and the P-type semiconductor layer 14 includes but is not limited to a P-type gallium nitride layer. The flip-chip Mini-LED chip forms a first DBR layer 17 around the core structure that wraps the core structure, thereby protecting the N-type semiconductor layer 12 and other film layers, so that the DE deep etching process can be removed during the preparation of the core structure, thereby achieving the purpose of improving the luminous efficiency of the flip-chip Mini-LED chip, reducing the chip size, and increasing the service life. In addition, the first DBR layer 17 exposes part of the surface of the first pad 15 and part of the surface of the second pad 16, ensuring that the flip-chip Mini-LED chip can achieve normal electrical connection with external components without affecting the use of the flip-chip Mini-LED chip.

[0047] In an optional embodiment of the present invention, the first DBR layer 17 is prepared based on an ALD (Atomic layer Deposition) process.

[0048] Specifically, in the embodiment of the present invention, the ALD process is a technology that selectively and alternately exposes different precursors to the surface of the substrate, causing them to chemically adsorb and react on the surface to form a deposited film. The core of the ALD process lies in its self-limiting nature, that is, the amount of material deposited in each cycle is the same, thereby ensuring precise control of the thickness and composition of the film. Its advantages include: precise control, that is, the ability to control the thickness and composition of the film with atomic-level precision; complex shape processing, that is, coatings suitable for complex shapes and porous materials, with the same coating thickness inside and on the surface; material diversity, that is, a variety of materials can be prepared, including binary, ternary and even more complex components.

[0049] In other words, in the embodiment of the present application, the use of the ‌ALD process to prepare the first DBR layer 17 can achieve high-quality film deposition on the exposed side walls and surfaces of the N-type semiconductor layer 12, even on the vertical side walls, thereby protecting the exposed N-type semiconductor layer 12, so that the DE deep etching process can be removed in the process of preparing the core particle structure, thereby achieving the purpose of improving the luminous efficiency of the flip-chip Mini-LED chip, reducing the chip size and increasing the service life, that is, the preparation of risk-free, smaller-sized, and more luminous-efficient flip-chip Mini-LED chips can be achieved.

[0050] In an optional embodiment of the present invention, the first DBR layer 17 includes first film layers and second film layers that are alternately arranged.

[0051] The refractive index of the first film layer is different from the refractive index of the second film layer.

[0052] Specifically, in the embodiment of the present invention, the refractive index range of the first film layer is 1.38-1.67; the refractive index range of the second film layer is 1.97-2.35. In other words, the first film layer can be understood as a low refractive index film layer, and the second film layer can be understood as a high refractive index film layer. Exemplarily, the material of the first film layer includes but is not limited to MgF2, SiO2 or Al2O3; the material of the second film layer includes but is not limited to ZrO2, HfO2, Ta2O5, ZnS or TiO2; in the embodiment of the present invention, the material of the first film layer is Al2O3 as an example for description, and the material of the second film layer is HfO2 as an example for description.

[0053] Optionally, based on the ALD process, Al2O3 film layers and HfO2 film layers are periodically and alternately deposited, and by optimizing their periodic ratio, as well as parameters such as the number of film layers and thickness, a first DBR layer 17 is formed that increases the transmittance of the blue light band and increases the reflectivity of the yellow light. This can improve the blue light output efficiency of the chip, and at the same time reflect the yellow light emitted by the phosphor, thereby improving the white light output efficiency.

[0054] In an optional embodiment of the present invention, reference Figure 2 , Figure 2 A schematic diagram of the structure of another flip-chip Mini-LED chip provided by an embodiment of the present invention. In the flip-chip Mini-LED chip provided by an embodiment of the present invention, the first DBR layer 17 also exposes the surface of the substrate 11 away from the N-type semiconductor layer 12 .

[0055] The flip-chip Mini-LED chip further includes:

[0056] The reflective layer 18 is located on the side of the first DBR layer 17 away from the core structure.

[0057] Specifically, in the embodiment of the present invention, a reflective layer 18 is formed again on the basis of the first DBR layer 17, and the surface of the substrate 11 facing away from the N-type semiconductor layer 12 is exposed, so as to realize the single-sided light emission of the flip-chip Mini-LED chip. When the flip-chip Mini-LED chip is applied to the display panel, the light interference between adjacent flip-chip Mini-LED chips can be reduced, thereby improving the display accuracy of the display panel and making its contrast better.

[0058] Optionally, the material of the reflective layer 18 includes but is not limited to metal materials.

[0059] In an optional embodiment of the present invention, Figure 1 and Figure 2 As shown, the core particle structure provided by the embodiment of the present invention also includes:

[0060] The current blocking layer 19 located on the side of the P-type semiconductor layer 14 facing away from the substrate 11 is also referred to as a CB layer in the technical field.

[0061] The transparent conductive layer 20 is located on the side of the P-type semiconductor layer 14 away from the substrate 11, and covers the current blocking layer 19; the material of the transparent conductive layer 20 includes but is not limited to ITO material. When the material of the transparent conductive layer 20 is ITO material, the transparent conductive layer 20 is also referred to as an ITO layer in the technical field.

[0062] The first electrode 21 is located on the side of the N-type semiconductor layer 12 facing away from the substrate 11 , and the second electrode 22 is located on the side of the transparent conductive layer 20 facing away from the substrate 11 .

[0063] The core particle structure provided by the embodiment of the present invention also includes: a second DBR layer 23, the second DBR layer 23 exposes part of the surface of the first electrode 21 and the second electrode 22; the first pad 15 is electrically connected to the N-type semiconductor layer 12 through the first electrode 21, and the first electrode 21 is also referred to as the N-electrode in the present technical field; the second pad 16 is electrically connected to the P-type semiconductor layer 14 through the second electrode 22 and the transparent conductive layer 20, and the second electrode 22 is also referred to as the P-electrode in the present technical field.

[0064] The materials of the first electrode 21 and the second electrode 22 can be the same or different, and the materials of the first pad 15 and the second pad 16 can be the same or different, which is not limited in the embodiment of the present invention.

[0065] It should be noted that the flip-chip Mini-LED chip provided in the embodiment of the present invention may also include other functional film layers, which will not be described one by one here.

[0066] based on Figure 1For the flip-chip Mini-LED chip shown, the first DBR layer 17 covers the side walls of the substrate 11, the surface of the substrate 11 facing away from the N-type semiconductor layer 12, the side walls of the N-type semiconductor layer 12, the side walls and exposed surface of the second DBR layer 23, and part of the side walls of the first pad 15 and the second pad 16.

[0067] based on Figure 2 For the flip-chip Mini-LED chip shown, the first DBR layer 17 covers the side walls of the substrate 11, the side walls of the N-type semiconductor layer 12, the side walls and exposed surfaces of the second DBR layer 23, and part of the side walls of the first pad 15 and the second pad 16.

[0068] Based on the above embodiments of the present invention, another embodiment of the present invention further provides a method for preparing a flip-chip Mini-LED chip, referring to Figure 3 , Figure 3 A schematic diagram of a process for preparing a flip-chip Mini-LED chip provided in an embodiment of the present invention. A method for preparing a flip-chip Mini-LED chip provided in an embodiment of the present invention comprises:

[0069] S101: providing a substrate 11.

[0070] Specifically, in the embodiment of the present invention, the substrate 11 includes but is not limited to a sapphire substrate.

[0071] S102 : forming an N-type semiconductor layer 12 , a multi-quantum well layer 13 , and a P-type semiconductor layer 14 stacked in sequence on one side of the substrate 11 .

[0072] Specifically, in the embodiment of the present invention, an N-type semiconductor layer 12, a multi-quantum well layer 13 and a P-type semiconductor layer 14 are formed on one side of the substrate 11, which are stacked in sequence; the formed epitaxial structure is cleaned, including but not limited to preparing a MESA photolithography pattern through processes such as photoresist coating, exposure, and development, including but not limited to etching out a MESA area through an ICP process, and after removing the photoresist, a portion of the N-type semiconductor layer 12 is exposed.

[0073] Optionally, including but not limited to using a PECVD process to deposit an insulating layer with a thickness ranging from 2300 angstroms to 10000 angstroms, including but not limited to using a positive photoresist as a mask, including but not limited to using a wet etching method to process the insulating layer, removing the photoresist after etching, and forming the required current blocking layer 19. The material of the current blocking layer 19 includes but is not limited to SiO2.

[0074] Optionally, including but not limited to using a sputtering process to deposit a transparent conductive layer 20 with a thickness ranging from 200 angstroms to 1100 angstroms; including but not limited to annealing the transparent conductive layer 20 in a rapid annealing furnace, with an annealing temperature ranging from 500°C to 650°C and an annealing time ranging from 1min to 10min to improve the film quality.

[0075] Optionally, including but not limited to using a negative photoresist as a mask, including but not limited to performing metal evaporation by electron beam evaporation to form a metal film layer with a thickness ranging from 1.3um to 2.1um, and performing metal stripping and photoresist removal after evaporation to form the first electrode 21 and the second electrode 22.

[0076] Optionally, the second DBR layer 23 is evaporated.

[0077] Optionally, including but not limited to using positive photoresist, the thickness of the photoresist is in the range of 12μm-18μm, performing soft baking treatment at a soft baking temperature range of 90℃-100℃ and a soft baking time range of 100s-300s, performing exposure treatment at an exposure amount range of 270mj-400mj, performing development treatment at a development time range of 80s-160s, performing hardening treatment at a hardening temperature range of 100℃-140℃ and a hardening time range of 15min-40min, and forming a mask. Including but not limited to using an ICP process to dry-etch the second DBR layer 23, after removing the photoresist, forming a DBR hole that exposes the first electrode 21 and the second electrode 22.

[0078] S103 : forming a first pad 15 and a second pad 16 , wherein the first pad 15 is electrically connected to the N-type semiconductor layer 12 , and the second pad 16 is electrically connected to the P-type semiconductor layer 14 .

[0079] Specifically, the embodiments of the present invention include but are not limited to using a negative photoresist as a mask, including but not limited to metal evaporation by electron beam evaporation to form a metal film layer with a thickness ranging from 1.3um to 2.1um, and performing metal stripping and photoresist removal after evaporation to form a first pad 15 and a second pad 16.

[0080] S104: performing cutting processing to form a plurality of independent core particle structures.

[0081] Specifically, in the embodiment of the present invention, including but not limited to electrical sampling, the substrate 11 is thinned to a thickness in the range of 100 μm-120 μm, and a cutting process is performed based on the MESA area to form a plurality of independent core particle structures.

[0082] S105: Figure 4 and Figure 5 As shown, a first DBR layer 17 is formed, the first DBR layer 17 wraps the core particle structure, and the first DBR layer 17 exposes a portion of the surface of the first pad 15 and a portion of the surface of the second pad 16 .

[0083] Specifically, in the embodiment of the present invention, the first DBR layer 17 is formed based on the ALD process but is not limited thereto. First, the core structure is tested and the AOI appearance is inspected. Then, Figure 4 As shown, the core particle structure that meets the requirements is fixed on a UV film 24 that is resistant to 200°C. Figure 5 As shown, the UV film 24 with the core particle structure is placed in the ALD machine, and the molecular adsorption technology is used to deposit the periodically alternating Al2O3 film layer and HfO2 film layer in an environment of 150°C to realize the preparation of the first DBR layer 17. After the first DBR layer 17 is prepared, the UV film 24 is debonded by UV light, and the chip on the UV film 24 is transferred to the carrier substrate by the reverse molding method for use, so as to realize the following Figure 1 Preparation of flip-chip Mini-LED chip shown.

[0084] In an optional embodiment of the present invention, reference Figure 6 , Figure 6 A schematic flow chart of another method for preparing a flip-chip Mini-LED chip provided by an embodiment of the present invention. In order to achieve single-sided light emission of a flip-chip Mini-LED chip, after preparing the first DBR layer 17, a method for preparing a flip-chip Mini-LED chip provided by an embodiment of the present invention further includes:

[0085] S106: Figure 7 As shown, a reflective layer 18 is formed on the side of the first DBR layer 17 away from the core structure.

[0086] S107: Figure 8 As shown, a portion of the reflective layer 18 and the first DBR layer 17 are removed to expose the surface of the substrate 11 facing away from the N-type semiconductor layer 12 .

[0087] Specifically, in the embodiment of the present invention, the reflectivity of the first DBR layer 17 can be improved by optimizing the periodic ratio, the number of film layers, the thickness and other parameters. Figure 7 As shown, a layer of metal is evaporated on the surface to form a reflective layer 18, and then Figure 8As shown, the first DBR layer 17 and the reflective layer 18 on the surface of the substrate 11 facing away from the N-type semiconductor layer 12 are removed by grinding and polishing, and then DI cleaning is performed, the UV film 24 is debonded by UV light, and the chip on the UV film 24 is transferred to the carrier substrate by a reverse molding method for use, so as to achieve the following. Figure 2 Preparation of flip-chip Mini-LED chip shown.

[0088] Based on the above embodiments of the present invention, a lighting device is provided in another embodiment of the present invention. The lighting device includes the flip-chip Mini-LED chip described in the above embodiments.

[0089] The above is a detailed introduction to a flip-chip Mini-LED chip and its preparation method and lighting equipment provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technicians in this field, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0090] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0091] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0092] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flip-chip Mini-LED chip, characterized in that: The flip-chip Mini-LED chip comprises: A core structure; the core structure comprises a substrate; an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer which are located on one side of the substrate and are stacked in sequence; and a first pad electrically connected to the N-type semiconductor layer, and a second pad electrically connected to the P-type semiconductor layer; A first DBR layer is provided to wrap the core particle structure, wherein the first DBR layer exposes a portion of the surface of the first pad and a portion of the surface of the second pad.

2. The flip-chip Mini-LED chip according to claim 1, characterized in that: The first DBR layer is prepared based on the ALD process.

3. The flip-chip Mini-LED chip according to claim 1, characterized in that: The first DBR layer includes first film layers and second film layers that are alternately arranged; The refractive index of the first film layer is different from the refractive index of the second film layer.

4. The flip-chip Mini-LED chip according to claim 3, characterized in that: The refractive index of the first film layer is in the range of 1.38-1.67; The refractive index of the second film layer is in the range of 1.97-2.

35.

5. The flip-chip Mini-LED chip according to claim 3, characterized in that: The material of the first film layer is MgF2, SiO2 or Al2O3; The material of the second film layer is ZrO2, HfO2, Ta2O5, ZnS or TiO2.

6. The flip-chip Mini-LED chip according to any one of claims 1 to 5, characterized in that: The first DBR layer also exposes a surface of the substrate facing away from the N-type semiconductor layer; The flip-chip Mini-LED chip further includes: A reflective layer is located on a side of the first DBR layer away from the core structure.

7. A method for preparing a flip-chip Mini-LED chip, characterized in that: The method for preparing the flip-chip Mini-LED chip comprises: providing a substrate; Forming an N-type semiconductor layer, a multi-quantum well layer, and a P-type semiconductor layer stacked in sequence on one side of the substrate; forming a first pad and a second pad, wherein the first pad is electrically connected to the N-type semiconductor layer, and the second pad is electrically connected to the P-type semiconductor layer; Performing cutting processing to form multiple independent core particle structures; A first DBR layer is formed, wherein the first DBR layer wraps the core particle structure, and the first DBR layer exposes a portion of the surface of the first pad and a portion of the surface of the second pad.

8. The method for preparing a flip-chip Mini-LED chip according to claim 7, characterized in that: The forming of the first DBR layer comprises: The first DBR layer is formed based on an ALD process.

9. The method for preparing a flip-chip Mini-LED chip according to claim 7 or 8, characterized in that: The method for preparing the flip-chip Mini-LED chip further includes: forming a reflective layer on a side of the first DBR layer away from the core structure; Part of the reflective layer and the first DBR layer is removed to expose a surface of the substrate facing away from the N-type semiconductor layer.

10. A lighting device, characterized in that: The lighting device comprises the flip-chip Mini-LED chip according to any one of claims 1-6.

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