A light emitting element and a method for preparing the same

Abstract

The present application provides a light-emitting element and a preparation method thereof. The light-emitting direction of the light-emitting element is a first direction. The light-emitting element comprises: a first substrate, a first light-emitting structure and a reflective film, wherein the first light-emitting structure is arranged on a side of the first substrate away from the first direction; the reflective film comprises a first part and a second part which are arranged continuously, wherein the first part covers the side wall of the first light-emitting structure, and the second part covers the side wall of the first substrate. The light-emitting element provided by the present application improves the problem of lateral optical crosstalk generated by a plurality of adjacent light-emitting elements in a light-emitting mode by arranging the first part covering the side wall of the first light-emitting structure and the second part covering the side wall of the first substrate in the reflective film.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a light-emitting element and a method for preparing the same. Background Art

[0002] Light Emitting Diode (LED) is an electroluminescent semiconductor light-emitting device. It has been widely used in the fields of automobiles, lighting, displays, medical treatment, optical communications, etc. due to its advantages such as low energy consumption, small size, long life, good stability, fast response, and stable luminous wavelength.

[0003] Taking the automotive field as an example, the basic functions of traditional vehicle-mounted LED light sources are driving information prompts and night lighting. However, with the development of the times, users have put forward more advanced functional requirements for vehicle-mounted LED light sources, such as high-precision local dimming function, low-power local highlight function and intelligent light projection display function.

[0004] However, in the related art, in the LED matrix of the vehicle-mounted LED light source, multiple adjacent light-emitting elements will produce the problem of lateral optical crosstalk in the light-emitting mode, which makes the vehicle-mounted LED light source unable to effectively meet the user's high-level functional requirements for the vehicle-mounted LED light source. This problem needs to be solved urgently. Summary of the invention

[0005] The present application provides a light-emitting element and a method for preparing the same, which can effectively solve the problem of lateral optical crosstalk generated by a plurality of adjacent light-emitting elements in a light-emitting mode in the related art.

[0006] In a first aspect, the present application provides a light-emitting element, wherein the light-emitting direction of the light-emitting element is a first direction, and the light-emitting element includes:

[0007] a first substrate;

[0008] A first light emitting structure is arranged on a side of the first substrate away from the first direction;

[0009] The reflective film comprises a first part and a second part which are continuously arranged, wherein the first part covers the side wall of the first light emitting structure, and the second part covers the side wall of the first substrate.

[0010] Optionally, the first substrate includes a sapphire substrate, wherein in the first direction, a side wall of the first light emitting structure is flush with a side wall of the first substrate.

[0011] Optionally, the reflective film includes a first non-metallic material layer and a second non-metallic material layer, the first non-metallic material layer includes a first refractive index material, the second non-metallic material layer includes a second refractive index material, and the first refractive index material and the second refractive index material have different refractive indices.

[0012] Optionally, the material with a higher refractive index between the first refractive index material and the second refractive index material is tantalum pentoxide.

[0013] Optionally, the first light-emitting structure includes a buffer layer, a first type semiconductor layer, an active layer, a second type semiconductor layer, a current spreading layer, an ohmic contact layer, a current blocking layer and a pad layer stacked in sequence on a side of the first substrate away from the first direction, the pad layer includes a first type pad and a second type pad, the reflective film covers the current blocking layer and includes a first through hole exposing the first type pad and a second through hole exposing the second type pad.

[0014] In a second aspect, the present application provides a method for preparing a light-emitting element, the method for preparing a light-emitting element comprising:

[0015] Providing an initial substrate, forming a plurality of first light-emitting structures spaced apart from each other in a first region of the initial substrate, wherein a distance between an edge of the first region and an edge of the initial substrate is greater than a first preset value, and a distance between any two adjacent first light-emitting structures is greater than twice the first preset value;

[0016] Forming a plurality of first grooves spaced apart from each other on the initial substrate, wherein each of the first grooves surrounds one of the first light-emitting structures, and the groove width of the first groove is equal to the first preset value, and the groove depth of the first groove is less than the thickness of the initial substrate;

[0017] forming a reflective film on the initial substrate, wherein the reflective film at least covers the side wall of each of the first light-emitting structures and the first side wall of each of the first grooves, and the first side wall is the side wall of the first groove close to the first light-emitting structure;

[0018] The initial substrate is thinned to separate the initial substrate into a plurality of first substrates that are independently arranged, and the side walls of the first substrates are covered by the reflective film.

[0019] Optionally, the step of forming a plurality of first grooves spaced apart from each other on the initial substrate includes:

[0020] Using a femtosecond laser to process a local area of ​​the initial substrate, so that an etching rate of the local area in a first etching method is greater than an etching rate of other areas in the first etching method;

[0021] Wherein, the initial substrate is a sapphire substrate.

[0022] Optionally, in the step of forming a plurality of first grooves spaced apart from each other on the initial substrate, after the step of treating a local area of ​​the initial substrate with a femtosecond laser, the step further includes:

[0023] Etching the initial substrate in the first etching mode to form a plurality of first grooves spaced apart from each other on the initial substrate, wherein the local area corresponds to an area where the plurality of first grooves are located;

[0024] Wherein, the first etching method includes inductively coupled plasma etching.

[0025] Optionally, in the step of forming a plurality of first grooves spaced apart from each other on the initial substrate, in a direction perpendicular to the initial substrate, a first side wall of each first groove is flush with a side wall of the corresponding first light-emitting structure.

[0026] Optionally, the step of forming a reflective film on the initial substrate includes:

[0027] Atomic layer deposition is used to sequentially form a first non-metallic material layer and a second non-metallic material layer on the initial substrate, wherein the first non-metallic material layer includes a first refractive index material, the second non-metallic material layer includes a second refractive index material, the first refractive index material and the second refractive index material have different refractive indices, and the material with a higher refractive index between the first refractive index material and the second refractive index material is tantalum pentoxide.

[0028] Beneficial effects of this application:

[0029] The present application provides a light-emitting element and a preparation method thereof. The light-emitting direction of the light-emitting element is a first direction. The light-emitting element comprises: a first substrate, a first light-emitting structure and a reflective film, wherein the first light-emitting structure is arranged on a side of the first substrate away from the first direction; the reflective film comprises a first part and a second part which are arranged continuously, wherein the first part covers the side wall of the first light-emitting structure, and the second part covers the side wall of the first substrate. The light-emitting element provided by the present application improves the problem of lateral optical crosstalk generated by a plurality of adjacent light-emitting elements in a light-emitting mode by arranging the first part covering the side wall of the first light-emitting structure and the second part covering the side wall of the first substrate in the reflective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A cross-sectional schematic diagram of a light-emitting element provided in an embodiment of the present application.

[0032] Figure 2 A cross-sectional schematic diagram of a reflective film provided in an embodiment of the present application.

[0033] Figure 3 A schematic diagram of the process of preparing a light-emitting element provided in an embodiment of the present application.

[0034] Figures 4 to 10 This is a cross-sectional schematic diagram corresponding to steps S01-1 to S01-7 of the method for preparing a light-emitting element provided in an embodiment of the present application.

[0035] Figure 11 to Figure 12 This is a cross-sectional schematic diagram corresponding to steps S02-1 to S02-2 of the method for preparing a light-emitting element provided in an embodiment of the present application.

[0036] Figure 13 to Figure 14 This is a cross-sectional schematic diagram corresponding to steps S03-1 to S03-2 of the method for preparing a light-emitting element provided in an embodiment of the present application.

[0037] Figures 15 to 18 This is a cross-sectional schematic diagram corresponding to steps S04-1 to S04-4 of the method for preparing a light-emitting element provided in an embodiment of the present application.

[0038] Description of reference numerals:

[0039] Light-emitting element 100; first substrate 10; side wall 101 of the first substrate; first light-emitting structure 20; side wall 201 of the first light-emitting structure; buffer layer 21; first type semiconductor layer 22; active layer 23; second type semiconductor layer 24; current spreading layer 25; ohmic contact layer 26; first ohmic contact portion 261; second ohmic contact portion 262; current blocking layer 27; pad layer 28; first type pad 281; second type pad 282; reflective film 30; first portion 301; second portion 302; first non-metallic material layer 31; second non-metallic material layer 32; protective film 40; blue film 50; first direction Y; initial substrate M1; first area A1; modified area A2; independent unit B1; first through hole H1; second through hole H2; first groove H3; first preset value m; DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words such as "upper" and "lower" used generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0041] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the present application 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. The following is described in detail respectively, and it should be noted that the description order of the following embodiments is not used as a limitation to the preferred order of the embodiments.

[0042] Figure 1 This is a cross-sectional schematic diagram of a light emitting element provided in an embodiment of the present application. Figure 1As shown, in the first aspect, an embodiment of the present application provides a light-emitting element 100, the light emitting direction of the light-emitting element 100 is a first direction Y, the light-emitting element 100 includes a first substrate 10, a first light-emitting structure 20 and a reflective film 30, wherein the first light-emitting structure 20 is arranged on a side of the first substrate 10 away from the first direction Y; the reflective film 30 includes a first part 301 and a second part 302 that are continuously arranged, the first part 301 covers the side wall 201 of the first light-emitting structure 20, and the second part 302 covers the side wall 101 of the first substrate 10.

[0043] In the light-emitting element 100 provided in the embodiment of the present application, the first light-emitting structure 20 is used to generate the output light of the light-emitting element 100. When the output light of the light-emitting element 100 is laterally propagated to the adjacent light-emitting element 100 via the side wall 201 of the first light-emitting structure 20, lateral optical crosstalk is generated. The light-emitting element 100 provided in the present application, by providing the first part 301 covering the side wall 201 of the first light-emitting structure 20 in the reflective film 30, can use the first part 301 to reflect the light irradiated on the side wall 201 of the first light-emitting structure 20, thereby well improving the problem of lateral optical crosstalk in the related art.

[0044] Further, continue to refer to Figure 1 , the direction in which the first substrate 10 is away from the first light-emitting structure 20 is the first direction Y, that is, the direction in which the first substrate 10 is away from the first light-emitting structure 20 is the light-emitting direction of the light-emitting element 100. Therefore, if the emitted light of the light-emitting element 100 is to be emitted to the outside of the light-emitting element 100 as much as possible so as to be received and perceived by the user or device, it must first pass through the filtering effect of the first substrate 10, that is, first be incident on the first substrate 10. On this basis, in order to reduce light loss and improve the brightness of the light-emitting element 100, the first substrate 10 should have as high a transmittance as possible, for example, a transmittance of more than 90%. However, since the first substrate 10 has a high transmittance and the propagation direction of the light incident into the first substrate 10 is not fixed, this may cause the light incident into the first substrate 10 to propagate laterally into the adjacent light-emitting element 100, thereby generating lateral optical crosstalk. The light-emitting element 100 provided in the present application further improves the problem of lateral optical crosstalk in the related art by setting a second portion 302 covering the side wall 101 of the first substrate 10 in the reflective film 30, so that the second portion 302 can be used to reflect the light irradiated onto the side wall 101 of the first substrate 10, thereby.

[0045] In summary, the light-emitting element 100 provided in the present application can effectively solve the problem of lateral optical crosstalk generated by adjacent multiple light-emitting elements 100 in the light-emitting mode in the related art. In order to highlight the importance of improving the problem of lateral optical crosstalk generated by adjacent multiple light-emitting elements 100 in the light-emitting mode in the related art, the following briefly introduces the high-precision local dimming function, low-power local highlight function and intelligent light projection display function in vehicle-mounted applications. The precision local dimming function includes: the light-emitting elements 100 in the light-emitting matrix can automatically light up or turn off, brighten or dim with extremely fine resolution according to traffic conditions. For example, when oncoming traffic is detected, the light-emitting elements 100 in the corresponding area will automatically turn off to avoid dazzling the other driver with strong light; the low-power local highlight function includes: high-precision control to turn off one or more areas, and other areas are illuminated at the highest brightness to reduce power consumption; the high-intelligence light projection display function includes: by projecting high-definition quality light onto the road, to display prompt symbols or warning information to drivers or other road users, such as displaying various types of welcome scenes when users approach the vehicle.

[0046] In addition, in the reflective film 30 provided in the present application, since the first part 301 and the second part 302 are both part of the reflective film 30, and the first part 301 and the second part 302 are continuously arranged, the first part 301 and the second part 302 can be formed through one process, thereby improving the production efficiency of the light-emitting element 100 and reducing the production cost of the light-emitting element 100.

[0047] In some embodiments of the present application, the first substrate 10 is a non-metallic material, and the first substrate 10 includes a sapphire substrate, wherein in the first direction Y, the side wall 201 of the first light-emitting structure 20 is flush with the side wall 101 of the first substrate 10 .

[0048] In the light-emitting element 100 provided in the embodiment of the present application, the first substrate 10 is a sapphire substrate, which has excellent light transmittance and can maintain the light extraction efficiency of the light-emitting element 100 at a high level. However, the sapphire substrate has excellent thermal stability, chemical inertness and high hardness, which makes it difficult to pattern the sapphire substrate by mechanical processing or chemical methods. The relevant technology generally adopts an overall cutting method to split the sapphire substrate into multiple independent sapphire substrates, and then invert and rearrange the sapphire substrates and the light-emitting structures thereon, and then coat and polish the reflective layer. The light-emitting element 100 formed in this way has a complex process and low production efficiency, and the sidewalls of the light-emitting structure on the sapphire substrate are usually not flush with the sidewalls of the sapphire substrate. When the first substrate 10 is a sapphire substrate, the light-emitting element 100 provided in the embodiment of the present application can have a structural feature in which the side wall 201 of the first light-emitting structure 20 is flush with the side wall 101 of the first substrate 10 through a simpler and more efficient preparation process, thereby reducing the volume of the light-emitting element 100 while ensuring the light-emitting area and light-emitting effect.

[0049] In some embodiments of the present application, the light emitting element 100 has a flip-chip structure.

[0050] Figure 2 A cross-sectional schematic diagram of a reflective film provided in an embodiment of the present application. Figure 1 and Figure 2 As shown, in some embodiments of the present application, the reflective film 30 includes a first non-metallic material layer 31 and a second non-metallic material layer 32, the first non-metallic material layer 31 includes a first refractive index material, the second non-metallic material layer 32 includes a second refractive index material, and the refractive indices of the first refractive index material and the second refractive index material are different.

[0051] In the light-emitting element 100 provided in the embodiment of the present application, the first non-metallic material layer 31 and the second non-metallic material layer 32 in the reflective film 30 are stacked. The present application does not limit the number of the first non-metallic material layer 31 and the second non-metallic material layer 32. When the first non-metallic material layer 31 and / or the second non-metallic material layer 32 are multiple, the first non-metallic material layer 31 and the second non-metallic material layer 32 are alternately stacked.

[0052] In the light-emitting element 100 provided in the embodiment of the present application, since the refractive index of the first refractive index material in the first non-metallic material layer 31 and the second refractive index material in the second non-metallic material layer 32 are different, a distributed Bragg reflector structure can be formed in the reflective film 30, and then the reflective film 30 is used to reflect the light irradiated on the side wall 201 of the first light-emitting structure 20 and the light irradiated on the side wall 101 of the first substrate 10, thereby improving the lateral optical crosstalk problem, and compared with the reflection method of doping nano reflective particles in the silicon adhesive, the reflection efficiency is greatly improved. In addition, since the first non-metallic material layer 31 and the second non-metallic material layer 32 in the reflective film 30 are both non-metallic materials, it is possible to reduce the difficulty of attaching the reflective film 30 on the first substrate 10, improve the film forming quality of the reflective film 30, and avoid the problem of increased manufacturing difficulty and damage to the packaging structure caused by the use of a metal reflective layer.

[0053] In some embodiments of the present application, the material with a higher refractive index between the first refractive index material and the second refractive index material is tantalum pentoxide.

[0054] In the light-emitting element 100 provided in the embodiment of the present application, the first non-metallic material layer 31 and the second non-metallic material layer 32 are both formed by atomic layer deposition, so that the thickness of the first non-metallic material layer 31 and the second non-metallic material layer 32 is more accurate. In the related art, titanium dioxide high refractive index materials are widely used, but the applicant has found that the titanium dioxide high refractive index materials formed by atomic layer deposition are easy to photocatalyze. With the accumulation of use time, in the presence of light and heat generated by the light-emitting structure, the titanium dioxide high refractive index material can react with carbon pollutants from the organic metal precursor to produce graphite, resulting in light efficiency loss. In the light-emitting element 100 provided in the embodiment of the present application, the tantalum pentoxide high refractive index material layer formed by atomic layer deposition will not be photocatalyzed, and can withstand the processing temperature of the atomic layer deposition method. Therefore, while ensuring the reflection effect of the reflective film 30, its stability can be improved to ensure the optical effect of the light-emitting element 100.

[0055] In some embodiments of the present application, the material with a lower refractive index between the first refractive index material and the second refractive index material is aluminum oxide.

[0056] In some embodiments of the present application, the first light-emitting structure 20 includes a buffer layer 21, a first type semiconductor layer 22, an active layer 23, a second type semiconductor layer 24, a current spreading layer 25, an ohmic contact layer 26, a current blocking layer 27 and a pad layer 28 which are sequentially stacked on a side of the first substrate 10 away from the first direction Y, the pad layer 28 includes a first type pad 281 and a second type pad 282, the reflective film 30 covers the current blocking layer 27 and includes a first through hole H1 exposing the first type pad 281 and a second through hole H2 exposing the second type pad 282.

[0057] In some embodiments of the present application, the buffer layer 21 may be U-type gallium nitride; the first type semiconductor layer 22 may be N-type gallium nitride; the active layer 23 may be a multiple quantum well layer (English full name: Multiple QuantumWell, abbreviated as: MQW); the second type semiconductor layer 24 may be P-type gallium nitride; the current spreading layer 25 may be indium tin oxide; the ohmic contact layer 26 may be a metal material, and the specific material is not limited; the current blocking layer 27 may be silicon dioxide or other insulating layers with good light transmittance; the pad layer 28 may be a metal material, and the specific material is not limited.

[0058] In a second aspect, an embodiment of the present application provides a method for preparing a light-emitting element 100 . Figure 3 A schematic diagram of a process for preparing a light-emitting element according to an embodiment of the present application. Figures 4 to 10 A schematic cross-sectional view corresponding to steps S01-1 to S01-7 of the method for preparing a light-emitting element provided in an embodiment of the present application; Figure 11 to Figure 12 A cross-sectional schematic diagram corresponding to steps S02-1 to S02-2 of the method for preparing a light-emitting element provided in an embodiment of the present application; Figure 13 to Figure 14 A schematic cross-sectional view corresponding to steps S03-1 to S03-2 of the method for preparing a light-emitting element provided in an embodiment of the present application; Figures 15 to 18 This is a cross-sectional schematic diagram corresponding to steps S04-1 to S04-4 of the method for preparing a light-emitting element provided in an embodiment of the present application. Figure 3-Figure 18 As shown, the method for preparing the light emitting element 100 includes step S01, step S02, step S03 and step S04.

[0059] Step S01 includes: providing an initial substrate M1, forming a plurality of first light-emitting structures 20 spaced apart from each other in a first area A1 of the initial substrate M1, wherein a distance between an edge of the first area A1 and an edge of the initial substrate M1 is greater than a first preset value m, and a distance between any two adjacent first light-emitting structures 20 is greater than twice the first preset value m.

[0060] Step S02 includes: forming a plurality of first grooves H3 spaced apart from each other on the initial substrate M1, wherein each first groove H3 surrounds a first light-emitting structure 20, and the groove width of the first groove H3 is equal to the first preset value m, and the groove depth of the first groove H3 is less than the thickness of the initial substrate M1.

[0061] Step S03 includes: forming a reflective film 30 on the initial substrate M1, wherein the reflective film 30 at least covers the sidewall 201 of each first light-emitting structure 20 and the first sidewall of each first groove H3, and the first sidewall is the sidewall 201 of the first groove H3 close to the first light-emitting structure 20.

[0062] Step S04 includes: performing a thinning process on the initial substrate M1 to separate the initial substrate M1 into a plurality of first substrates 10 independently arranged from each other, and the sidewalls 101 of the first substrates 10 are covered by the reflective film 30 .

[0063] In the light-emitting element 100 prepared by the method for preparing the light-emitting element 100 provided in the present application, since the reflective film 30 at least covers the side wall 201 of each of the first light-emitting structures 20 and the side wall 101 of the first substrate 10, it is possible to improve the problem of lateral optical crosstalk generated by multiple adjacent light-emitting elements 100 in the light-emitting mode, thereby improving the light emission effect of the light-emitting element 100.

[0064] In addition, in the related art, it is necessary to thin, grind, scratch, measure and sort the substrate where the multiple LED chips are located, and then invert the multiple LED chips and arrange them on a carrier, and then prepare the reflective film 30. The reflective film 30 will cover the side walls and light-emitting surface of the substrate where the LED chips are located. Therefore, it is necessary to remove the reflective film 30 on the light-emitting surface of the substrate by polishing, which greatly increases the manufacturing cost of the light-emitting element 100 and reduces the production efficiency.

[0065] The preparation method of the light-emitting element 100 provided in the embodiment of the present application is to expose the side wall 101 of the first substrate 10 by opening a plurality of first grooves H3 of a non-through structure on an initial substrate M1 formed with a plurality of first light-emitting structures 20. This method enables the initial substrate M1 to still have an integrated structure when the reflective film 30 is subsequently formed, while the reflective film 30 at least covers the side wall 201 of each first light-emitting structure 20 and the first side wall of each first groove H3. That is, the formation process of the reflective film 30 is completed before the separation process of the initial substrate M1 (the initial substrate M1 is thinned to separate the initial substrate M1 into a plurality of first substrates 10 independently arranged from each other). This can avoid the problem of complex process and low production efficiency caused by the formation process of the reflective film 30 being located after the separation process of the initial substrate M1 in the related art, thereby greatly improving the production efficiency and reducing the production cost.

[0066] In some embodiments of the present application, in step S01, a plurality of first light-emitting structures 20 spaced apart from each other are formed in the first area A1 of the initial substrate M1, and when the distance between the edge of the first area A1 and the edge of the initial substrate M1 is greater than the first preset value m, and the distance between any two adjacent first light-emitting structures 20 is greater than twice the first preset value m, the peripheral area of ​​the initial substrate M1 corresponding to any first light-emitting structure 20 has space for forming a first groove H3 with a groove width of the first preset value m. Thus, the subsequent step S02 can realize the formation of a plurality of first grooves H3 spaced apart from each other on the initial substrate M1, and each first groove H3 surrounds a first light-emitting structure 20, and the groove width of the first groove H3 is equal to the first preset value m.

[0067] Reference Figures 4 to 10 In some embodiments of the present application, in step S01, an initial substrate M1 is provided, and the step of forming a plurality of first light-emitting structures 20 spaced apart from each other in a first area A1 of the initial substrate M1 includes: step S01-1, step S01-2, step S01-3, step S01-4, step S01-5, step S01-6, and step S01-7.

[0068] Reference Figure 4 , step S01 - 1 includes: providing an initial substrate M1.

[0069] Reference Figure 5Step S01-2 includes: sequentially growing a buffer layer 21, a first type semiconductor layer 22, an active layer 23, and a second type semiconductor layer 24 on the initial substrate M1 by metal organic chemical vapor deposition (MOCVD) to form an epitaxial wafer.

[0070] Reference Figure 6 , step S01-3 includes: performing a first cleaning treatment on the epitaxial wafer, wherein the first cleaning treatment includes: first performing SPM solution cleaning, then performing pure water cleaning, and then performing dehydration and drying treatment; thereafter, performing a first etching treatment on the epitaxial wafer, wherein the first etching treatment includes: forming a patterned positive photoresist, performing step etching processing on the epitaxial wafer using an ICP process, etching until the first type semiconductor layer 22 is exposed, and then removing the positive photoresist and cleaning; thereafter, performing a second etching treatment on the epitaxial wafer to form a plurality of independent units B1 spaced apart from each other, wherein the second etching treatment includes: forming a patterned positive photoresist, etching the epitaxial wafer using an ICP process to form a plurality of independent units B1 spaced apart from each other on the initial substrate M1, and then removing the positive photoresist and cleaning.

[0071] Reference Figure 7 , step S01-4 includes: forming a patterned current spreading layer 25 on the second type semiconductor layer 24 of each independent unit B1, wherein the step of forming the current spreading layer 25 on the second type semiconductor layer 24 of each independent unit B1 includes: forming a current spreading layer 25 by magnetron sputtering, forming a patterned positive photoresist after annealing, patterning the current spreading layer 25 by wet etching, and then removing the positive photoresist and cleaning.

[0072] Reference Figure 8 , step S01-5 includes: forming a patterned ohmic contact layer 26, wherein the step of forming the ohmic contact layer 26 includes: forming a patterned negative photoresist, forming the patterned ohmic contact layer 26 by vacuum evaporation coating, and then removing the negative photoresist to strip off the unnecessary ohmic contact layer 26 and cleaning to form a patterned ohmic contact layer 26, wherein each independent unit B1 is correspondingly provided with two first ohmic contact portions 261 and second ohmic contact portions 262 arranged at intervals, the first ohmic contact portion 261 is located on the exposed first type semiconductor layer 22, and the second ohmic contact portion 262 is located on the current spreading layer 25.

[0073] Reference Fig. 9, step S01-6 includes: forming a patterned current blocking layer 27, wherein the step of forming a patterned current blocking layer 27 includes: forming a current blocking layer 27 by plasma enhanced vapor deposition, forming a patterned positive photoresist, patterning the current blocking layer 27 by an ICP process, and then removing the positive photoresist and cleaning to expose at least a portion of the first ohmic contact portion 261 and at least a portion of the second ohmic contact portion 262.

[0074] Reference Fig.10 , step S01-7 includes: forming a patterned pad layer 28, wherein the step of forming a patterned pad layer 28 includes: forming a patterned negative photoresist, forming the patterned pad layer 28 by vacuum evaporation coating, and then removing the negative photoresist to strip off the unnecessary pad layer 28 and cleaning to form a patterned pad layer 28, wherein each independent unit B1 is correspondingly provided with a first type pad 281 and a second type pad 282, the first type pad 281 is electrically connected to the first ohmic contact portion 261, and the second type pad 282 is electrically connected to the second ohmic contact portion 262.

[0075] Further, in step S01-7, the thickness of the pad layer 28 is greater than the thickness of the current blocking layer 27, the first type pad 281 protrudes from the current blocking layer 27 to expose the opening of the first ohmic contact portion 261, and the second type pad 282 protrudes from the current blocking layer 27 to expose the opening of the second ohmic contact portion 262. Further, the thickness of the pad layer 28 is greater than the sum of the thickness of the current blocking layer 27 and the thickness of the reflective film 30.

[0076] After step S01 is completed, a plurality of first light-emitting structures 20 spaced apart from each other are formed in the first area A1 of the initial substrate M1, wherein the first light-emitting structures 20 include a buffer layer 21, a first type semiconductor layer 22, an active layer 23, a second type semiconductor layer 24, a current spreading layer 25, an ohmic contact layer 26, a current blocking layer 27 and a pad layer 28 stacked in sequence on a side of the first substrate 10 away from the first direction Y, wherein the pad layer 28 includes a first type pad 281 and a second type pad 282.

[0077] In some embodiments of the present application, in step S02, since the depth of the first groove H3 is smaller than the thickness of the initial substrate M1, the first groove H3 is a non-through groove, so that in the subsequent step S04, the initial substrate M1 can be separated into a plurality of first substrates 10 independently arranged from each other only by thinning the initial substrate M1.

[0078] Reference Fig.11 In some embodiments of the present application, in step S02, the step of forming a plurality of first grooves H3 spaced apart from each other on the initial substrate M1 includes step S02-1: using a femtosecond laser to process a local area of ​​the initial substrate M1 so that the etching rate of the local area under the first etching method is greater than the etching rate of other areas under the first etching method; wherein the initial substrate M1 is a sapphire substrate.

[0079] In the preparation method of the light-emitting element 100 provided in the embodiment of the present application, the initial substrate M1 is a sapphire substrate, and the sapphire substrate has excellent thermal stability, chemical inertness and high hardness, making it difficult to pattern the sapphire substrate by mechanical processing or chemical methods, and because it is also necessary to form a non-through groove structure with a high aspect ratio and no cracks on the sapphire substrate, this greatly increases the difficulty of preparing the first groove H3. In step S02, the present application uses a low-energy pulsed femtosecond laser to treat a local area of ​​the initial substrate M1, so that the local area forms a modified area A2, improves the physicochemical activity of the local area, and then makes the etching rate of the local area under the first etching method greater than the etching rate of other areas under the first etching method. When the etching rate of the local area under the first etching method is greater than the etching rate of other areas under the first etching method, it can be formed on the initial substrate M1 by performing a first etching on the initial substrate M1 in the subsequent process, using the etching rate difference to form a plurality of first grooves H3 spaced from each other.

[0080] Reference Fig.12 In some embodiments of the present application, in step S02, in the step of forming a plurality of first grooves H3 spaced apart from each other on the initial substrate M1, after the step of processing a local area of ​​the initial substrate M1 using a femtosecond laser, it also includes a step S02-2: etching the initial substrate M1 under the first etching method to form a plurality of first grooves H3 spaced apart from each other on the initial substrate M1, the local area corresponding to the area where the plurality of first grooves H3 are located; wherein the first etching method includes inductively coupled plasma etching.

[0081] In the preparation method of the light-emitting element 100 provided in the embodiment of the present application, the first etching method includes inductively coupled plasma etching (English full name: Inductively Couple Plasma, abbreviated as: ICP). Inductively coupled plasma etching generates plasma by exciting gas through radio frequency power supply, which is the result of the joint action of physical process and chemical process. Under vacuum and low pressure, the radio frequency generated by the ICP radio frequency power supply is output to the annular coupling coil, and the gas mixed in a certain proportion is coupled to glow discharge to generate high-density plasma. Under the action of the RF radio frequency of the lower electrode, these plasmas bombard the surface of the substrate, and the chemical bonds of the substrate material are broken, and react with the etching gas to generate volatile substances, which are separated from the substrate in the form of gas and are pumped away from the vacuum pipeline. Inductive plasma etching can make good use of the characteristics of femtosecond laser to improve the physical and chemical activity of the local area, so that when the initial substrate M1 is subjected to inductively coupled plasma etching, the etching rate of the local area is greater than the etching rate of other areas, thereby forming a plurality of non-through first grooves H3 with high aspect ratio and no cracks on the initial substrate M1.

[0082] In some embodiments of the present application, in step S02, in the step of forming a plurality of first grooves H3 spaced apart from each other on the initial substrate M1, in a direction perpendicular to the initial substrate M1, a first side wall of each first groove H3 is flush with a side wall 201 of the corresponding first light-emitting structure 20.

[0083] In the preparation method of the light-emitting element 100 provided in the embodiment of the present application, a plurality of the first grooves H3 are formed by adopting a femtosecond laser + inductively coupled plasma etching method, which can greatly improve the position accuracy of the first groove H3, so that in step S02, a structure is achieved in which the first side wall of each of the first grooves H3 is flush with the side wall 201 of the corresponding first light-emitting structure 20 in a direction perpendicular to the initial substrate M1, thereby further reducing the size of the finally formed light-emitting element 100.

[0084] In some embodiments of the present application, in step S02, the step of forming a plurality of first grooves H3 spaced apart from each other on the initial substrate M1 includes: forming a patterned positive photoresist, using a low-energy pulsed femtosecond laser to treat a local area of ​​the initial substrate M1 so that the local area forms a modified area A2, thereby improving the physicochemical activity of the local area, thereby making the etching rate of the local area under the ICP process greater than the etching rate of other areas under the first etching method, and then patterning the initial substrate M1 using the ICP process, removing the positive photoresist and cleaning, so as to form a plurality of first grooves H3 in the local area of ​​the initial substrate M1, each of the first grooves H3 correspondingly surrounding one of the first light-emitting structures 20.

[0085] In some embodiments of the present application, in step S03, the step of forming a reflective film 30 on the initial substrate M1 includes: using atomic layer deposition to sequentially form a first non-metallic material layer 31 and a second non-metallic material layer 32 on the initial substrate M1, wherein the first non-metallic material layer 31 includes a first refractive index material, the second non-metallic material layer 32 includes a second refractive index material, the first refractive index material and the second refractive index material have different refractive indices, and the material with a higher refractive index between the first refractive index material and the second refractive index material is tantalum pentoxide.

[0086] In the method for preparing the light-emitting element 100 provided in the embodiment of the present application, in step S03, by adopting the atomic layer deposition method, the first non-metallic material layer 31 and the second non-metallic material layer 32 are sequentially formed on the initial substrate M1, which can achieve accurate control of the thickness of the first non-metallic material layer 31 and the thickness of the second non-metallic material layer 32. In addition, the tantalum pentoxide high-refractive index material layer formed by the atomic layer deposition method will not be photocatalyzed and can withstand the processing temperature of the atomic layer deposition method. Therefore, while ensuring the reflection effect of the reflective film 30, its stability can be improved to ensure the optical effect of the light-emitting element 100.

[0087] Reference Fig.13In some embodiments of the present application, in step S03, the step of forming a reflective film 30 on the initial substrate M1 includes step S03-1: using tantalum ethoxide and water as precursors for forming a first non-metallic material layer 31, and using trimethylaluminum and water as precursors for forming a second non-metallic material layer 32, pulses of tantalum ethoxide and water, methylaluminum and water are sequentially released into the reaction chamber, thereby forming a first non-metallic material layer 31 and a second non-metallic material layer 32 arranged in a stacked manner. In this case, the refractive index of the first refractive index material in the first non-metallic material layer 31 is greater than the second refractive index material in the second non-metallic material layer 32, the first refractive index material is tantalum pentoxide, and the second refractive index material is aluminum trioxide. It should be noted that when the first non-metallic material layer 31 and / or the second non-metallic material layer 32 are multiple layers, the first non-metallic material layer 31 and the second non-metallic material layer 32 are arranged alternately.

[0088] Reference Fig.14 In some embodiments of the present application, in step S03, the step of forming a reflective film 30 on the initial substrate M1 also includes step S03-2: forming a patterned positive photoresist, and patterning the stacked first non-metallic material layer 31 and the second non-metallic material layer 32 to form a reflective film 30 having a first through hole H1 and a second through hole H2, wherein the reflective film 30 covers the current blocking layer 27, the first through hole H1 exposes the first type pad 281, and the second through hole H2 exposes the second type pad 282.

[0089] Reference Figures 15 to 18 In some embodiments of the present application, in step S04, the step of thinning the initial substrate M1 to separate the initial substrate M1 into a plurality of first substrates 10 independently arranged from each other, and the sidewalls 101 of the first substrates 10 are covered by the reflective film 30 includes: step S04-1, step S04-2, step S04-3 and step S04-4.

[0090] Reference Fig.15 Step S04 - 1 includes: forming a protective film 40 on the reflective film 30 , wherein the protective film 40 is located on a side of the reflective film 30 away from the initial substrate M1 , and covers the reflective film 30 , the first type pad 281 , and the second type pad 282 .

[0091] Reference Fig.16 Step S04 - 2 includes: performing a thinning process on the initial substrate M1 , wherein the thinning process includes grinding, so that the initial substrate M1 is separated into a plurality of first substrates 10 independently arranged from each other, and the sidewalls 101 of the first substrates 10 are covered by the reflective film 30 .

[0092] Reference Fig.17 Step S04 - 3 includes: forming a blue film 50 on a side of the first substrate 10 away from the protective film 40 .

[0093] Reference Fig.18 Step S04 - 4 includes: removing the protective film 40 and other non-functional waste film layer structures to form a plurality of light-emitting elements 100 on the blue film 50 .

[0094] In summary, the present application provides a light-emitting element and a preparation method thereof, wherein the light-emitting direction of the light-emitting element is a first direction, and the light-emitting element comprises: a first substrate, a first light-emitting structure and a reflective film, wherein the first light-emitting structure is arranged on a side of the first substrate away from the first direction; the reflective film comprises a first part and a second part which are continuously arranged, wherein the first part covers the side wall of the first light-emitting structure, and the second part covers the side wall of the first substrate. The light-emitting element provided by the present application improves the problem of lateral optical crosstalk generated by multiple adjacent light-emitting elements in a light-emitting mode by arranging a first part covering the side wall of the first light-emitting structure and a second part covering the side wall of the first substrate in the reflective film.

[0095] The above is a detailed introduction to a light-emitting element and a preparation method thereof provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a light-emitting element, characterized in that: The method for preparing the light-emitting element comprises: Providing an initial substrate, forming a plurality of first light-emitting structures spaced apart from each other in a first region of the initial substrate, wherein a distance between an edge of the first region and an edge of the initial substrate is greater than a first preset value, and a distance between any two adjacent first light-emitting structures is greater than twice the first preset value; Forming a plurality of first grooves spaced apart from each other on the initial substrate, wherein each of the first grooves surrounds one of the first light-emitting structures, and the groove width of the first groove is equal to the first preset value, and the groove depth of the first groove is less than the thickness of the initial substrate; forming a reflective film on the initial substrate, wherein the reflective film at least covers the side wall of each of the first light-emitting structures and the first side wall of each of the first grooves, and the first side wall is the side wall of the first groove close to the first light-emitting structure; The initial substrate is thinned to separate the initial substrate into a plurality of first substrates independently arranged from each other, and the side walls of the first substrates are covered by the reflective film.

2. The method for preparing a light-emitting element according to claim 1, characterized in that: The step of forming a plurality of first grooves spaced apart from each other on the initial substrate comprises: Using a femtosecond laser to process a local area of ​​the initial substrate, so that an etching rate of the local area in a first etching method is greater than an etching rate of other areas in the first etching method; Wherein, the initial substrate is a sapphire substrate.

3. The method for preparing a light-emitting element according to claim 2, characterized in that: In the step of forming a plurality of first grooves spaced apart from each other on the initial substrate, after the step of treating a local area of ​​the initial substrate with a femtosecond laser, the method further comprises: Etching the initial substrate in the first etching mode to form a plurality of first grooves spaced apart from each other on the initial substrate, wherein the local area corresponds to an area where the plurality of first grooves are located; Wherein, the first etching method includes inductively coupled plasma etching.

4. The method for preparing a light-emitting element according to claim 3, characterized in that: In the step of forming a plurality of first grooves spaced apart from each other on the initial substrate, in a direction perpendicular to the initial substrate, a first side wall of each first groove is flush with a side wall of the corresponding first light emitting structure.

5. The method for preparing a light-emitting element according to claim 1, characterized in that: The step of forming a reflective film on the initial substrate comprises: Atomic layer deposition is used to sequentially form a first non-metallic material layer and a second non-metallic material layer on the initial substrate, wherein the first non-metallic material layer includes a first refractive index material, the second non-metallic material layer includes a second refractive index material, the first refractive index material and the second refractive index material have different refractive indices, and the material with a higher refractive index between the first refractive index material and the second refractive index material is tantalum pentoxide.

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