A light-emitting unit and a method for preparing the same

Abstract

The present application provides a light-emitting unit and a preparation method thereof. The preparation method of the light-emitting unit comprises: forming a plurality of LED light-emitting structures on a common substrate; performing laser cutting processing on the common substrate to form a plurality of independent substrates, each independent substrate being provided with an LED light-emitting structure, the independent substrate comprising a first smooth portion and a first rough portion, the first rough portion being located on a side of the first smooth portion away from the LED light-emitting structure; grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to remove the first rough portion and retain the first smooth portion; forming a reflective film, the reflective film covering a surface of each independent substrate on a side away from the LED light-emitting structure and a side wall of each independent substrate; grinding the reflective film from a side of the independent substrate away from the LED light-emitting structure to remove the reflective film covering a surface of each independent substrate on a side away from the LED light-emitting structure. The present application can improve the lateral light crosstalk problem of the light-emitting unit.

Description

Technical Field

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

[0002] Light Emitting Diode (LED) is an electroluminescent semiconductor light-emitting unit. It has been widely used in the fields of automobile, lighting, display, medical treatment, optical communication, etc. due to its advantages of low energy consumption, small size, long life, good stability, fast response, and stable wavelength. Taking the on-board LED light source with high market application value as an example, the traditional on-board intelligent high-beam headlight generally uses multiple to dozens of LED light-emitting structures to form a high-beam headlight lighting component as a light source, and independently controls the brightness adjustment or shutdown of each LED light-emitting structure through the driving circuit chip, and realizes functions such as follow-up steering, precise lighting, irradiation range control, and dynamic turn signal through different light distribution patterns.

[0003] With the development of the times, the market has put forward higher functional requirements for the functions of vehicle-mounted intelligent high-beam headlights, such as high-precision local dimming technology - it can automatically light up or turn off, brighten or dim with extremely fine resolution according to traffic conditions. Once oncoming traffic is detected, the LED light-emitting structure in the corresponding area will automatically turn off to avoid dazzling the other driver with strong light; high-intelligent light projection display - high-definition quality light is projected onto the wall and the road surface, and can project various images to the driver or other personnel, realizing entertainment functions such as outdoor cinemas and outdoor KTV, or displaying early warning information to improve driving safety. In this application context, it is necessary to improve the problem of lateral optical crosstalk of multiple adjacent LED light-emitting structures in the vehicle-mounted LED light source in the light-emitting mode as much as possible to meet the user's high-level functional requirements for vehicle-mounted LED light sources. The applicant found in internal research that the light output angle of the LED light-emitting structure can be narrowed by coating the side wall of the LED light-emitting structure with a reflective film, thereby improving the problem of lateral light crosstalk.

[0004] The applicant further discovered that in order to meet the requirements of vehicle-mounted LED light sources for light output efficiency, heat dissipation efficiency and stability, it is necessary to use a flip-chip LED chip with a substrate, and accordingly, a reflective film needs to be plated on the side wall of the substrate. During the production and preparation process of the flip-chip LED chip with a substrate, the substrate needs to be cut to form a plurality of independently arranged flip-chip LED chips, and the traditional cutting process will cause at least part of the side wall of the flip-chip LED chip to become rough. The rough side wall will reduce the film formation stability of the reflective film on the side wall of the substrate, and then cause problems such as peeling of the reflective film in subsequent process treatments, which seriously affects the reflective effect of the reflective film on the side wall of the substrate, making the lateral light crosstalk problem prominent and reducing product quality. Summary of the invention

[0005] The present application provides a light-emitting unit and a method for preparing the same, which can effectively solve the lateral light crosstalk problem existing in the light-emitting unit in the related art.

[0006] In a first aspect, the present application provides a method for preparing a light-emitting unit, the method comprising the following steps: forming a plurality of LED light-emitting structures on a common substrate; performing laser cutting processing on the common substrate to form a plurality of independent substrates, each of the independent substrates correspondingly provided with one of the LED light-emitting structures, wherein the independent substrate comprises a first smooth portion and a first rough portion, the first rough portion is located on a side of the first smooth portion away from the LED light-emitting structure, and the average roughness of the side wall of the first rough portion is greater than the average roughness of the side wall of the first smooth portion; grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to remove the first rough portion and retain at least a portion of the first smooth portion; forming a reflective film, the reflective film covering a surface of each of the independent substrates on a side away from the LED light-emitting structure and a side wall of each of the independent substrates; grinding the reflective film from a side of the independent substrate away from the LED light-emitting structure to remove the reflective film covering the surface of each of the independent substrates on a side away from the LED light-emitting structure.

[0007] Optionally, the step of performing laser cutting on the common substrate to form a plurality of independent substrates, each of which has a corresponding LED light-emitting structure, includes: fixing the depth of the focus of the laser cutting in the common substrate so that the focus is closer to the surface of the common substrate on a side away from the LED light-emitting structure.

[0008] Optionally, the step of laser cutting the common substrate to form a plurality of independent substrates, each of which has a corresponding LED light-emitting structure, includes: positioning the focus inside the common substrate to form a plurality of internal holes in the common substrate, with the centers of the internal holes closer to the surface of the common substrate on a side away from the LED light-emitting structure, applying pressure to the common substrate to form a plurality of independent substrates, each of which has a first smooth portion, a first rough portion, and a second smooth portion stacked in layers; wherein the thickness of the first smooth portion is greater than the thickness of the second smooth portion.

[0009] Optionally, the step of grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to remove the first rough portion and retaining at least a portion of the first smooth portion includes: grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to remove the second smooth portion and the first rough portion, and retaining at least a portion of the first smooth portion.

[0010] Optionally, the step of performing laser cutting processing on the common substrate to form a plurality of independent substrates, each of which has a corresponding LED light-emitting structure, includes: positioning the focus on the surface of the common substrate on a side away from the LED light-emitting structure to form a plurality of grooves on the surface of the common substrate on a side away from the LED light-emitting structure; and applying pressure to the common substrate to form a plurality of independent substrates, each of which has a first smooth portion and a first rough portion formed in a stacked manner.

[0011] Optionally, the thickness of the first smooth portion is greater than three times the thickness of the first rough portion.

[0012] Optionally, in the step of performing laser cutting processing on the common substrate to form a plurality of independent substrates, each of which is provided with a corresponding LED light-emitting structure, the side walls of the independent substrates are located on the outside of the side walls of the LED light-emitting structure; in the step of forming a reflective film, the reflective film covers the surface of each independent substrate on a side away from the LED light-emitting structure and the side walls of each independent substrate, the reflective film also covers the surface of each independent substrate on a side close to the LED light-emitting structure.

[0013] Optionally, in the step of forming a reflective film, wherein the reflective film covers the surface of each independent substrate on a side away from the LED light-emitting structure and the side wall of each independent substrate, the reflective film includes a first reflective layer and a second reflective layer, and the second reflective layer is arranged on a side of the first reflective layer away from the independent substrate, and the refractive index of the second reflective layer is different from the refractive index of the first reflective layer.

[0014] Optionally, the step of forming a reflective film, wherein the reflective film covers the surface of each of the independent substrates on a side away from the LED light-emitting structure and the side wall of each of the independent substrates, comprises: using an atomic layer deposition method, at a temperature of 150° C. to 200° C., sequentially releasing a precursor of a first reflective layer and a precursor of a second reflective layer into a film forming chamber to form a first reflective layer and a second reflective layer stacked in sequence on the side wall of each of the independent substrates; wherein the precursor of the first reflective layer comprises a mixture of tantalum ethoxide and water, and the precursor of the second reflective layer comprises a mixture of trimethylaluminum and water.

[0015] In a second aspect, the present application provides a method for preparing a light-emitting unit, wherein the light-emitting unit is prepared by any of the methods for preparing a light-emitting unit described above.

[0016] The present application provides a light-emitting unit and a preparation method thereof, the preparation method of the light-emitting unit comprising the following steps: forming a plurality of LED light-emitting structures on a common substrate; performing laser cutting on the common substrate to form a plurality of independent substrates, each of the independent substrates correspondingly provided with one of the LED light-emitting structures, wherein the independent substrate comprises a first smooth portion and a first rough portion, the first rough portion is located on a side of the first smooth portion away from the LED light-emitting structure, and the average roughness of the side wall of the first rough portion is greater than the average roughness of the side wall of the first smooth portion; grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to remove The first rough portion retains at least a portion of the first smooth portion; a reflective film is formed, and the reflective film covers the surface of each independent substrate on a side away from the LED light-emitting structure and the side wall of each independent substrate; the reflective film is ground from the side of the independent substrate away from the LED light-emitting structure to remove the reflective film covering the surface of each independent substrate on a side away from the LED light-emitting structure. The present application can effectively improve the coating quality of the reflective film on the side wall of the independent substrate in the finally prepared light-emitting unit, thereby ensuring that the reflective film can well realize the function of narrowing the light output angle of the LED light-emitting structure, improve the lateral crosstalk problem, and improve product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0018] Figure 1 A schematic diagram of a process for preparing a light-emitting unit provided in some embodiments of the present application.

[0019] Figure 2 A simplified structural schematic diagram of a light-emitting unit provided in some embodiments of the present application.

[0020] Figure 3 A schematic cross-sectional view of an independent substrate after laser cutting process according to the first embodiment of the present application.

[0021] Figure 4 A structural schematic diagram corresponding to step S01 provided in an embodiment of the present application.

[0022] Figure 5 A structural schematic diagram corresponding to step S01-A provided in an embodiment of the present application.

[0023] Figure 6 A structural schematic diagram corresponding to step S02 provided in an embodiment of the present application.

[0024] Figure 7 This is a structural diagram corresponding to step S03 provided in an embodiment of the present application.

[0025] Figure 8 A structural schematic diagram corresponding to step S03-A provided in an embodiment of the present application.

[0026] Fig. 9 This is a schematic diagram of the structure corresponding to step S04 provided in an embodiment of the present application.

[0027] Fig.10 This is a schematic diagram of the structure corresponding to step S05 provided in an embodiment of the present application.

[0028] Fig.11 A schematic cross-sectional view of an independent substrate after laser cutting process according to the second embodiment of the present application.

[0029] Description of reference numerals:

[0030] Common substrate 100; white film 200; grinding special film material 300; blue film 400; coating special film material 500; independent substrate 10; LED light-emitting structure 20; buffer layer 21; N-type semiconductor layer 22; active layer 23; P-type semiconductor layer 24; current spreading layer 25; ohmic contact layer 26; current blocking layer 27; electrode layer 28; reflective film 30; first smooth portion P1; second smooth portion P2; first rough portion C1; first direction Y. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than 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.

[0032] The terms "first" and "second" in this document are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] 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, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0035] Embodiment 1

[0036] Figure 1 A schematic diagram of a process for preparing a light-emitting unit provided in some embodiments of the present application; Figure 2 A simplified structural schematic diagram of a light-emitting unit provided in some embodiments of the present application; Figure 3 This is a schematic cross-sectional view of an independent substrate 10 after laser cutting process provided in the first embodiment of the present application. Figure 1 , Figure 2 and Figure 3 As shown, the first embodiment of the present application provides a method for preparing a light-emitting unit, and the method for preparing the light-emitting unit includes step S01, step S02, step S03, step S04 and step S05.

[0037] Step S01 includes: forming a plurality of LED light emitting structures 20 on a common substrate 100 .

[0038] Step S02 includes: performing laser cutting processing on the common substrate 100 to form a plurality of independent substrates 10, each of the independent substrates 10 correspondingly provided with one of the LED light-emitting structures 20, wherein the independent substrate 10 includes a first smooth portion P1 and a first rough portion C1, the first rough portion C1 is located on a side of the first smooth portion P1 away from the LED light-emitting structure 20, and the average roughness of the side wall of the first rough portion C1 is greater than the average roughness of the side wall of the first smooth portion P1.

[0039] Step S03 includes: grinding the independent substrate 10 from a side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the first rough portion C1 and retain at least a portion of the first smooth portion P1.

[0040] Step S04 includes: forming a reflective film 30, wherein the reflective film 30 covers a surface of each of the independent substrates 10 away from the LED light-emitting structure 20 and a side wall of each of the independent substrates 10;

[0041] Step S05 includes grinding the reflective film 30 from a side of the independent substrate 10 away from the LED light emitting structure 20 to remove the reflective film 30 covering the surface of each independent substrate 10 away from the LED light emitting structure 20 .

[0042] In the preparation method of the light-emitting unit provided in the present application, the purpose of step S01 and step S02 is to batch form a plurality of light-emitting units with basic light-emitting functions, so as to reduce process costs and improve production efficiency. Here, the light-emitting unit with basic light-emitting functions can be understood as a combination structure composed of an independent substrate 10 and an LED light-emitting structure 20 on the independent substrate 10. The formation of multiple independent substrates 10 depends on the laser cutting process, because the laser cutting process has the advantages of high processing accuracy, high cutting efficiency, and strong versatility. However, the applicant has found that the laser cutting process, such as the laser stress induced cutting process, will form a rough explosion point structure on the side wall of the independent substrate 10. The rough explosion point structure will at least produce the adverse consequence of reducing the adhesion quality of the reflective film 30 on the side wall of the independent substrate 10 when the reflective film 30 is subsequently formed, and become the inducement for the reflective film 30 to peel off after the grinding process.

[0043] On this basis, in the process step of forming the reflective film 30 corresponding to step S04, the reflective film 30 covers the surface of each independent substrate 10 on the side away from the LED light-emitting structure 20 and the side wall of each independent substrate 10, that is, the reflective film 30 is formed on the surface and side wall of the independent substrate 10 at one time by overall coating. Although this overall coating method can reduce the difficulty of sidewall coating, it will also increase the process steps, that is, it is necessary to additionally add step S05 to remove the reflective film 30 covering the surface of each independent substrate 10 on the side away from the LED light-emitting structure 20 to ensure normal light emission of the light-emitting unit. The method for removing the reflective film 30 covering the surface of each of the independent substrates 10 on the side away from the LED light-emitting structure 20 is grinding. The applicant has found in internal research that the grinding method can ensure that the reflective film 30 covering the surface of each of the independent substrates 10 on the side away from the LED light-emitting structure 20 is completely removed. However, since the adhesion quality of the reflective film 30 on the side wall of the independent substrate 10 has deteriorated, the adhesion quality of the reflective film 30 on the side wall of the independent substrate 10 will be further seriously deteriorated during the grinding process, which will cause the problem of peeling of the reflective film 30, seriously affecting the reflection effect of the reflective film 30 on the side wall of the independent substrate 10, making the lateral light crosstalk problem prominent and reducing product quality.

[0044] Reference Figure 3 As shown, the applicant has found through verification that although the laser cutting process will produce a rough explosion point structure, the rough explosion point structure is concentrated within a certain depth range, such as concentrated within Figure 3The side wall within the second depth range R2 on one side of the rough explosion point structure within the first depth range R1 shown is relatively smooth, and the laser cutting process can be controlled so that the side wall of the rough explosion point structure located within the second depth range R2 faces the first direction Y, and the first direction Y is the direction of the LED light-emitting structure 20 toward the independent substrate 10. Then, through step S03, the independent substrate 10 can be ground from the side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the first rough portion C1 in the first depth range R1 and retain at least a portion of the first smooth portion P1 in the second depth range R2. Since the first rough portion C1 with a higher average roughness has been removed before executing step S04, the film forming quality of the reflective film 30 covering the side wall of each of the independent substrates 10 in step S04 can be greatly improved, thereby avoiding the problem of serious deterioration of the adhesion quality of the reflective film 30 on the side wall of the independent substrate 10 caused by the grinding operation performed in step S05, and thus the coating quality of the reflective film 30 on the side wall of the independent substrate 10 in the finally prepared light-emitting unit can be effectively improved, thereby ensuring that the reflective film 30 can well realize the function of narrowing the light output angle of the LED light-emitting structure 20, improve the lateral crosstalk problem, and improve product quality.

[0045] In some embodiments of the present application, in step S02, the common substrate 100 is laser cut to form a plurality of independent substrates 10, each of which has a corresponding LED light-emitting structure 20, including: fixing the depth of the focus of the laser cutting in the common substrate 100 so that the focus is closer to the surface of the common substrate 100 away from the LED light-emitting structure 20.

[0046] In the method for preparing the light-emitting unit provided in the embodiment of the present application, the focus of laser cutting is the focus of the laser emitted by the laser cutting device on the common substrate 100 when the laser cutting process is performed by the laser cutting device. The depth area corresponding to the focus of laser cutting is the laser energy concentration area. The common substrate 100 in the depth area corresponding to the focus will have a strong thermal impact. After the laser cutting process is completed, a rough heat-affected interface will be generated in the depth area corresponding to the focus of laser cutting on the side wall of the independent substrate 10. The first rough portion C1 includes the rough heat-affected zone interface. Therefore, when the focus is made closer to the surface of the side of the common substrate 10 away from the LED light-emitting structure 20, the rough heat-affected interface can be made as far away from the LED light-emitting structure 20 as possible, and then, the second depth range R2 is expanded, so that the thickness of the first smooth portion P1 is increased, and then the area of ​​the reflective film 30 subsequently formed on the side wall of the independent substrate 10 is increased, and the reflective film 30 is enhanced. The narrowing effect of the light output angle of the LED light-emitting structure 20 is enhanced, and the lateral light crosstalk problem is further improved, and the product quality is improved.

[0047] In some embodiments of the present application, in step S02, the step of laser cutting the common substrate 100 to form a plurality of independent substrates 10, each of which has a first smooth portion P1 and a first rough portion C1 stacked in a stacked manner, includes: positioning the focus inside the common substrate 100 to form a plurality of internal holes in the common substrate 100, with the centers of the internal holes being closer to the surface of the common substrate 100 on a side away from the LED light-emitting structure 20, applying pressure to the common substrate 100 to form a plurality of independent substrates 10, each of which has a first smooth portion P1, a first rough portion C1, and a second smooth portion P2 stacked in a stacked manner; wherein the thickness of the first smooth portion P1 is greater than the thickness of the second smooth portion P2.

[0048] Reference Figure 3 As shown, the first smooth portion P1 of the second depth range R2, the first rough portion C1 of the first depth range R1, and the second smooth portion P2 of the third depth range R3 are stacked in sequence in the first direction Y, that is, the first rough portion C1 of the first depth range R1 is located in the middle area of ​​the independent substrate 10.

[0049] In the preparation method of the light-emitting unit provided in the embodiment of the present application, the laser cutting processing method is laser stress induced cutting, that is, a short-pulse laser beam is used to penetrate the surface of the common substrate 100 and focus on the inside of the common substrate 100. Since the instantaneous energy of the short-pulse laser is extremely high, the laser beam is concentrated inside the common substrate 100 to form a plurality of internal holes, and the internal holes are distributed in a grid-like manner in a plane direction parallel to the common substrate 100, and the depth of the internal holes in the common substrate 100 is fixed. Therefore, external pressure can be applied to the common substrate 100, specifically, external pressure can be applied to each grid area of ​​the common substrate 100, so that the common substrate 100 is broken from the depth area where the internal holes are located and extends to both sides, thereby forming a first rough portion C1 of the first depth range R1 in the middle area of ​​the independent substrate 10, and forming a plurality of light-emitting units with basic light-emitting functions.

[0050] In addition, since the present application makes the center of the internal hole closer to the surface of the common substrate 100 away from the LED light-emitting structure 20, the center of the first rough portion C1 formed subsequently can be further away from the LED light-emitting structure 20, so that the thickness of the first smooth portion P1 is greater than the thickness of the second smooth portion P2, and the thickness of the first smooth portion P1 is larger, which helps to reduce the grinding accuracy in the subsequent step S05 and increase the overall thickness of the independent substrate 10 in the subsequent product, thereby increasing the area of ​​the reflective film 30 subsequently formed on the side wall of the independent substrate 10, enhancing the narrowing effect of the reflective film 30 on the light output angle of the LED light-emitting structure 20, improving the lateral light crosstalk problem, and improving product quality.

[0051] In some embodiments of the present application, a thickness of the first smooth portion P1 is greater than a sum of thicknesses of the first rough portion C1 and the second smooth portion P2.

[0052] In the method for preparing the light-emitting unit provided in the embodiment of the present application, the depth of the focus inside the common substrate 100 can be controlled so that the thickness of the first smooth portion P1 is greater than the sum of the thicknesses of the first rough portion C1 and the second smooth portion P2, thereby making the thickness of the first smooth portion P1 larger, which helps to further reduce the grinding accuracy in the subsequent step S05 and increase the overall thickness of the independent substrate 10 in the subsequent product, thereby further increasing the area of ​​the reflective film 30 subsequently formed on the side wall of the independent substrate 10, enhancing the effect of the reflective film 30 on narrowing the light output angle of the LED light-emitting structure 20, improving the problem of lateral light crosstalk, and improving product quality.

[0053] In some embodiments of the present application, in step S03, the step of grinding the independent substrate 10 from a side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the first rough portion C1 and retaining at least a portion of the first smooth portion P1 includes: grinding the independent substrate 10 from a side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the second smooth portion P2 and the first rough portion C1 and retaining at least a portion of the first smooth portion P1.

[0054] In the method for preparing the light-emitting unit provided in the embodiment of the present application, after step S02, each of the independent substrates 10 is formed with a first smooth portion P1, a first rough portion C1, and a second smooth portion P2 stacked in layers, and the second smooth portion P2 is arranged on the side of the first rough portion C1 away from the first smooth portion P1. When the independent substrate 10 is ground from the side of the independent substrate 10 away from the LED light-emitting structure 20, the second smooth portion P2 needs to be removed first before the first rough portion C1 can be further removed, thereby ensuring that the reflective film 30 subsequently formed on the side wall of the independent substrate 10 has a high coating quality. Therefore, the present application needs to reduce the thickness of the second smooth portion P2 as much as possible to reduce the grinding cost.

[0055] In some embodiments of the present application, in the step of laser cutting the common substrate 100 to form a plurality of independent substrates 10, each of which is provided with a corresponding LED light-emitting structure 20, the sidewalls of the independent substrates 10 are located on the outside of the sidewalls of the LED light-emitting structure 20; in the step of forming a reflective film 30, the reflective film 30 covers the surface of each independent substrate 10 on a side away from the LED light-emitting structure 20 and the sidewalls of each independent substrate 10, the reflective film 30 also covers the surface of each independent substrate 10 on a side close to the LED light-emitting structure 20.

[0056] In the method for preparing the light-emitting unit provided in the embodiment of the present application, in the step of laser cutting the common substrate 100 to form a plurality of independent substrates 10, each of which has a corresponding LED light-emitting structure 20, the sidewall of the independent substrate 10 is located outside the sidewall of the LED light-emitting structure 20, that is, the size of the prepared independent substrate 10 is slightly larger than the size of the LED light-emitting structure 20, which means that in the process of laser cutting the common substrate 100, the accuracy requirements for laser cutting can be reduced, and damage to the film layer in the LED light-emitting structure 20 caused by laser cutting can be avoided as much as possible, thereby improving the product yield. However, the size of the prepared independent substrate 10 is slightly larger than the size of the LED light-emitting structure 20, which means that at least part of the surface of the independent substrate 10 close to the LED light-emitting structure 20 is not covered by the LED light-emitting structure 20. Therefore, in the step of forming the reflective film 30, wherein the reflective film 30 covers the surface of each independent substrate 10 on the side away from the LED light-emitting structure 20 and the side wall of each independent substrate 10, the reflective film 30 also covers the surface of each independent substrate 10 on the side close to the LED light-emitting structure 20 to avoid light leakage problems.

[0057] As mentioned above, the reflective film 30 is coated as a whole, specifically, each independent substrate 10 together with the LED light-emitting structure 20 is placed in a film forming chamber, and the reflective film 30 is deposited on the exposed areas of the independent substrate 10 and the LED light-emitting structure 20. When a rough blast point structure exists on the side wall of the independent substrate 10, it will directly affect the continuity between the reflective film 30 on the side wall of the independent substrate 10 and the reflective film 30 on the surface of the side close to the LED light-emitting structure 20, which may easily cause problems such as light leakage and reduced reliability. Since the common substrate 100 is laser cut to form a plurality of independent substrates 10, each independent substrate 10 is provided with a corresponding LED light-emitting structure 20, and the depth of the focus of laser cutting in the common substrate 100 is fixed, after the laser cutting process, the depth range of the rough blast point structure on the side wall of the independent substrate 10 is also fixed, that is, the rough blast point structure on the side wall of the independent substrate 10 only includes the first rough portion C1, and since the first rough portion C1 has been removed during the grinding of the independent substrate 10, the present application can ensure the continuity between the reflective film 30 on the side wall of the independent substrate 10 and the reflective film 30 on the surface of the side close to the LED light-emitting structure 20, thereby improving the reliability of the light-emitting unit and avoiding light leakage problems.

[0058] In some embodiments of the present application, in the step of forming a reflective film 30, wherein the reflective film 30 covers the surface of a side of each of the independent substrates 10 away from the LED light-emitting structure 20 and the sidewalls of each of the independent substrates 10, the reflective film 30 includes a first reflective layer (not shown in the figure) and a second reflective layer (not shown in the figure), wherein the second reflective layer is disposed on a side of the first reflective layer away from the independent substrate 10, and the refractive index of the second reflective layer is different from the refractive index of the first reflective layer.

[0059] In the method for preparing the light-emitting unit provided in the embodiment of the present application, the reflective film 30 includes a first reflective layer and a second reflective layer which are stacked and have different refractive indices, that is, the reflective film 30 is a distributed Bragg reflector, thereby effectively improving the reliability of the light-emitting unit. However, the reflective film 30 achieves the light reflection effect through the cooperation between the first reflective layer and the second reflective layer. However, the applicant unexpectedly discovered that when there is a rough explosive point structure on the side wall of the independent substrate 10, that is, when there is the first rough portion C1, the reflection effect of the distributed Bragg reflector will be seriously reduced. The present application grinds the independent substrate 10 to remove the first rough portion C1, so that the reflection effect of the reflective film 30 can be taken into account while ensuring the reliability of the light-emitting unit, thereby effectively improving the problem of lateral light crosstalk.

[0060] In some embodiments of the present application, in step S04, the step of forming a reflective film 30, wherein the reflective film 30 covers the surface of each independent substrate 10 on a side away from the LED light-emitting structure 20 and the side wall of each independent substrate 10, comprises: using an atomic layer deposition method, at a temperature of 150° C. to 200° C., sequentially releasing a precursor of a first reflective layer and a precursor of a second reflective layer into a film forming chamber to form a first reflective layer and a second reflective layer stacked in sequence on the side wall of each independent substrate 10; wherein the precursor of the first reflective layer comprises a mixture of tantalum ethoxide and water, and the precursor of the second reflective layer comprises a mixture of trimethylaluminum and water.

[0061] In the preparation method of the light-emitting unit provided in the embodiment of the present application, the applicant discovered in internal research that one of the reflective layers in a conventional distributed Bragg reflector is usually a titanium dioxide layer, and the titanium dioxide layer is produced by photocatalysis in the process. During the actual use of the light-emitting unit, under the dual effects of blue light and heat generated by the LED light-emitting structure 20, the titanium dioxide layer can react with carbon pollutants from the organic metal precursor to produce graphite and other substances that affect the luminous efficiency of the light-emitting unit. The present application adopts an atomic layer deposition method to sequentially release the precursor of the first reflective layer and the precursor of the second reflective layer into a film forming chamber under the condition of 150°C to 200°C, so as to form a first reflective layer and a second reflective layer stacked in sequence on the side wall of each of the independent substrates 10. Since the precursor of the first reflective layer includes a mixture of tantalum ethanol and water, and the precursor of the second reflective layer includes a mixture of trimethylaluminum and water, a first reflective layer of tantalum pentoxide and a second reflective layer of aluminum trioxide can be prepared. While ensuring a high refractive index difference between the first reflective layer and the second reflective layer, the use of a titanium dioxide layer can be avoided, thereby ensuring the light efficiency of the light-emitting unit and extending the service life of the light-emitting unit.

[0062] In some embodiments of the present application, the first reflective layer is made of tantalum pentoxide, and the second reflective layer is made of aluminum trioxide, wherein the thickness of the first reflective layer is greater than the thickness of the second reflective layer, so as to improve the coating stability while ensuring the reflection effect.

[0063] Figure 4 This is a schematic diagram of the structure corresponding to step S01 provided in the embodiment of the present application. Figure 4 As shown, step S01 includes: forming a plurality of LED light-emitting structures 20 on a common substrate 100, wherein the LED light-emitting structures 20 include a buffer layer 21, an N-type semiconductor layer 22, an active layer 23, a P-type semiconductor layer 24, a current spreading layer 25, an ohmic contact layer 26, a current blocking layer 27 and an electrode layer 28 which are sequentially stacked on the common substrate 100. Optionally, the common substrate 100 is a sapphire substrate, and the thickness of the common substrate 100 is greater than 500 microns.

[0064] Figure 5 This is a schematic diagram of the structure corresponding to step S01-A provided in the embodiment of the present application. Figure 5 As shown, after step S01 and before step S02, step S01-A is further included, and step S01-A includes: grinding the common substrate 100 to reduce the thickness of the common substrate 100. Optionally, the thickness of the common substrate 100 can be reduced to 150 microns to 250 microns.

[0065] Figure 6 The schematic diagram of the structure corresponding to step S02 provided in the embodiment of the present application. Figure 3 and Figure 6 As shown, step S02 includes: fixing the side of the common substrate 100 away from the LED light-emitting structure 20 on the white film 200, using laser irradiation cutting lines, laser cutting the common substrate 100 by laser stress induced cutting, and then extruding the cutting lines in a vertical direction by a cleaver to form a plurality of independent substrates 10, each of which has a corresponding LED light-emitting structure 20, wherein the independent substrate 10 includes a first smooth portion P1 and a first rough portion C1, the first rough portion C1 is located on a side of the first smooth portion P1 away from the LED light-emitting structure 20, and the average roughness of the side wall of the first rough portion C1 is greater than the average roughness of the side wall of the first smooth portion P1.

[0066] Figure 7 This is a schematic diagram of the structure corresponding to step S03 provided in the embodiment of the present application. Figure 7 As shown, step S03 includes: rearranging and fixing the light-emitting unit (independent substrate 10+LED light-emitting structure 20) with basic light-emitting function onto a grinding-specific film material 300, wherein the LED light-emitting structure 20 is buried in the grinding-specific film material 300, and only the independent substrate 10 is exposed, wherein the size of the independent substrate 10 is larger than the size of the LED light-emitting structure 20, so as to facilitate the positioning of the independent substrate 10 and the uniformity of the horizontality of each independent substrate 10; then, grinding the independent substrate 10 from the side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the first rough portion C1 and retain at least a portion of the first smooth portion P1; then, cleaning the independent substrate 10, and the cleaning agent may be pure water.

[0067] Figure 8 This is a schematic diagram of the structure corresponding to step S03-A provided in the embodiment of the present application. Figure 8 As shown, after step S03 and before step S04, step S03-A includes: treating the grinding-specific film material 300 by thermal decomposition or ultraviolet light treatment, so as to invert the light-emitting unit with basic light-emitting function onto the blue film 400, and perform point measurement and sorting.

[0068] Fig. 9 This is a schematic diagram of the structure corresponding to step S04 provided in the embodiment of the present application. Fig. 9As shown, step S04 includes: rearranging and fixing the light-emitting units with basic light-emitting functions that have been point-measured and sorted onto a coating-specific film material 500, wherein a portion of the LED light-emitting structure 20 is buried in the coating-specific film material 500, exposing a first portion of the side wall of the LED light-emitting structure 20 and the independent substrate 10, the first portion can be the side wall of the LED light-emitting structure 20 corresponding to the P-type semiconductor layer 24+active layer 23+N-type semiconductor layer 22+buffer layer 21, and then forming a reflective film 30, the reflective film 30 covers the surface of each of the independent substrates 10 away from the LED light-emitting structure 20, the side wall of each of the independent substrates 10, the surface of each of the independent substrates 10 facing the LED light-emitting structure 20, and the first portion of the side wall of the LED light-emitting structure 20.

[0069] Fig.10 This is a schematic diagram of the structure corresponding to step S05 provided in the embodiment of the present application. Fig.10 As shown, step S05 includes: treating the coating-specific film material 500 by ultraviolet light treatment to reduce its adhesion to the LED light-emitting structure 20, so that the light-emitting unit with basic light-emitting function can be transferred and fixed on a grinding-specific film material 300 by using a sorting machine, and then grinding the reflective film 30 from the side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the reflective film 30 covering the surface of each independent substrate 10 away from the LED light-emitting structure 20.

[0070] Continue to refer to Figure 2 As shown, in the second aspect, embodiment 1 of the present application provides a light-emitting unit, which includes an independent substrate 10 and an LED light-emitting structure 20 stacked in sequence, and a reflective film 30 covering the side wall of the independent substrate 10, and the light-emitting unit is prepared by the preparation method of the light-emitting unit described above.

[0071] Embodiment 2

[0072] Fig.11 This is a schematic cross-sectional view of an independent substrate 10 after laser cutting process provided in the second embodiment of the present application. Figure 1 , Figure 2 and Fig.11 As shown, in the first aspect, Embodiment 2 of the present application provides a method for preparing a light-emitting unit, and the method for preparing the light-emitting unit includes step S01, step S02, step S03, step S04 and step S05.

[0073] Step S01 includes: forming a plurality of LED light emitting structures 20 on a common substrate 100 .

[0074] Step S02 includes: performing laser cutting processing on the common substrate 100 to form a plurality of independent substrates 10, each of the independent substrates 10 correspondingly provided with one of the LED light-emitting structures 20, wherein the independent substrate 10 includes a first smooth portion P1 and a first rough portion C1, the first rough portion C1 is located on a side of the first smooth portion P1 away from the LED light-emitting structure 20, and the average roughness of the side wall of the first rough portion C1 is greater than the average roughness of the side wall of the first smooth portion P1.

[0075] Step S03 includes: grinding the independent substrate 10 from a side of the independent substrate 10 away from the LED light-emitting structure 20 to remove the first rough portion C1 and retain at least a portion of the first smooth portion P1.

[0076] Step S04 includes: forming a reflective film 30, wherein the reflective film 30 covers a surface of each of the independent substrates 10 away from the LED light-emitting structure 20 and a side wall of each of the independent substrates 10;

[0077] Step S05 includes grinding the reflective film 30 from a side of the independent substrate 10 away from the LED light emitting structure 20 to remove the reflective film 30 covering the surface of each independent substrate 10 away from the LED light emitting structure 20 .

[0078] It should be noted that the preparation method of the light-emitting unit provided in the second embodiment of the present application is similar to the preparation method of the light-emitting unit provided in the first embodiment of the present application, and the same parts will not be repeated in the second embodiment of the present application.

[0079] In some embodiments of the present application, in step S02, the common substrate 100 is laser cut to form a plurality of independent substrates 10, each of which has a corresponding LED light-emitting structure 20, including: positioning the focus on the surface of the common substrate 100 away from the LED light-emitting structure 20 to form a plurality of grooves on the surface of the common substrate 100 away from the LED light-emitting structure 20; and applying pressure to the common substrate 100 to form a plurality of independent substrates 10, each of which has a first smooth portion P1 and a first rough portion C1 stacked in a stack.

[0080] In the preparation method of the light-emitting unit provided in the embodiment of the present application, the laser cutting processing method is laser surface ablation cutting, that is, a short-pulse laser or an ultra-short-pulse laser beam is focused on the surface of the common substrate 100 away from the LED light-emitting structure 20, and the focused area absorbs the laser energy to form a removal melting and evaporation, thereby forming a plurality of grooves on the surface of the common substrate 100 away from the LED light-emitting structure 20, and then the common substrate 100 is disconnected at each groove by applying pressure to the common substrate 100 from the outside, thereby obtaining a plurality of light-emitting units with basic light-emitting functions.

[0081] In addition, since the present application adopts a processing method in which the focus is located on the surface of the common substrate 100 away from the LED light-emitting structure 20, the first rough portion C1 in each subsequently formed independent substrate 10 can be away from the surface of the first smooth portion P1, that is, the surface of the independent substrate 10 away from the LED light-emitting structure 20, that is, the independent substrate 10 no longer includes the second smooth portion P2, which can further increase the thickness of the first smooth portion P1, and help to reduce the grinding accuracy in the subsequent step S15, and increase the overall thickness of the independent substrate 10 in the subsequent product, thereby increasing the area of ​​the reflective film 30 subsequently formed on the side wall of the independent substrate 10, enhancing the narrowing effect of the reflective film 30 on the light output angle of the LED light-emitting structure 20, improving the lateral light crosstalk problem, and improving product quality.

[0082] In some embodiments of the present application, a thickness of the first smooth portion P1 is greater than three times a thickness of the first rough portion C1.

[0083] Reference Fig.11 In the preparation method of the light-emitting unit provided in the embodiment of the present application, the first smooth portion P1 of the second depth range R2 and the first rough portion C1 of the first depth range R1 are stacked in a first direction Y, and the first direction Y is the direction of the LED light-emitting structure 20 toward the independent substrate 10. The thickness of the first smooth portion P1 is greater than three times the thickness of the first rough portion C1, that is, the second depth range R2 is greater than three times the thickness of the first depth range R1.

[0084] In the method for preparing the light-emitting unit provided in the embodiment of the present application, the thickness of the first rough portion C1 can be precisely controlled by controlling the depth of the groove by controlling the laser cutting process, and when the thickness of the first rough portion C1 is determined, the thickness of the first smooth portion P1 is also determined. The present application makes the thickness of the first smooth portion P1 greater than three times the thickness of the first rough portion C1, so that the thickness of the first smooth portion P1 can be maintained above a preset thickness, thereby ensuring the narrowing effect of the reflective film 30 on the light output angle of the LED light-emitting structure 20, improving the lateral light crosstalk, and making the yield control of the method for preparing the light-emitting unit more accurate. Exemplarily, the thickness of the first rough portion C1 is 20-40 microns, and the thickness of the first smooth portion P1 is 100-120 microns.

[0085] Continue to refer to Figure 2 As shown, in the second aspect, embodiment 1 of the present application provides a light-emitting unit, which includes an independent substrate 10 and an LED light-emitting structure 20 stacked in sequence, and a reflective film 30 covering the side wall of the independent substrate 10, and the light-emitting unit is prepared by the preparation method of the light-emitting unit described above.

[0086] In summary, the present application provides a light-emitting unit and a method for preparing the same, the method for preparing the light-emitting unit comprising the following steps: forming a plurality of LED light-emitting structures on a common substrate; performing laser cutting on the common substrate to form a plurality of independent substrates, each of the independent substrates correspondingly provided with one of the LED light-emitting structures, wherein the independent substrate comprises a first smooth portion and a first rough portion, the first rough portion being located on a side of the first smooth portion away from the LED light-emitting structure, and the average roughness of the side wall of the first rough portion is greater than the average roughness of the side wall of the first smooth portion; grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to obtain a plurality of LED light-emitting structures; The first rough portion is removed, and at least a portion of the first smooth portion is retained; a reflective film is formed, and the reflective film covers the surface of each of the independent substrates on a side away from the LED light-emitting structure and the side wall of each of the independent substrates; the reflective film is ground from the side of the independent substrate away from the LED light-emitting structure to remove the reflective film covering the surface of each of the independent substrates on a side away from the LED light-emitting structure. The present application can effectively improve the coating quality of the reflective film on the side wall of the independent substrate in the finally prepared light-emitting unit, thereby ensuring that the reflective film can well realize the function of narrowing the light output angle of the LED light-emitting structure, improve the lateral crosstalk problem, and improve product quality.

[0087] The above is a detailed introduction to a light-emitting unit 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 unit, characterized in that: The method for preparing the light-emitting unit comprises the following steps: forming a plurality of LED light-emitting structures on a common substrate; The common substrate is laser cut to form a plurality of independent substrates, each of which is provided with one LED light-emitting structure, wherein the independent substrate comprises a first smooth portion and a first rough portion, the first rough portion is located on a side of the first smooth portion away from the LED light-emitting structure, and the average roughness of the side wall of the first rough portion is greater than the average roughness of the side wall of the first smooth portion; wherein the size of the independent substrate is greater than the size of the LED light-emitting structure; Rearrange and fix the plurality of independent substrates together with the LED light-emitting structures thereon onto a grinding-specific film material, wherein the LED light-emitting structures are buried in the grinding-specific film material, and only the independent substrates are exposed; and grind the independent substrates from a side of the independent substrates away from the LED light-emitting structures to remove the first rough portion and retain at least a portion of the first smooth portion; Forming a reflective film, the reflective film covering the surface of each of the independent substrates on a side away from the LED light-emitting structure and the sidewall of each of the independent substrates, wherein the reflective film disposed on the sidewall of the independent substrate comprises a first reflective layer and a second reflective layer which are stacked and have different refractive indices, the first reflective layer is made of tantalum pentoxide, the second reflective layer is made of aluminum trioxide, and the thickness of the first reflective layer is greater than the thickness of the second reflective layer; The reflective film is ground from a side of the independent substrate away from the LED light-emitting structure to remove the reflective film covering a surface of each independent substrate away from the LED light-emitting structure.

2. The method for preparing the light-emitting unit according to claim 1, characterized in that: The step of laser cutting the common substrate to form a plurality of independent substrates, each of which has an LED light-emitting structure disposed thereon, comprises: The depth of the focal point of the laser cutting in the common substrate is fixed so that the focal point is closer to the surface of the common substrate on a side away from the LED light-emitting structure.

3. The method for preparing the light-emitting unit according to claim 2, characterized in that: The step of laser cutting the common substrate to form a plurality of independent substrates, each of which has an LED light-emitting structure disposed thereon, comprises: The focus is located inside the common substrate to form a plurality of internal holes in the common substrate, and the centers of the internal holes are closer to the surface of the common substrate on a side away from the LED light-emitting structure, and pressure is applied to the common substrate to form a plurality of independent substrates, and each of the independent substrates is formed with a first smooth portion, a first rough portion, and a second smooth portion that are stacked; wherein the thickness of the first smooth portion is greater than the thickness of the second smooth portion.

4. The method for preparing the light-emitting unit according to claim 3, characterized in that: The step of grinding the independent substrate from a side of the independent substrate away from the LED light-emitting structure to remove the first rough portion and retain at least a portion of the first smooth portion comprises: The independent substrate is ground from a side of the independent substrate away from the LED light-emitting structure to remove the second smooth portion and the first rough portion, and at least a portion of the first smooth portion is retained.

5. The method for preparing a light-emitting unit according to claim 2, characterized in that: The step of laser cutting the common substrate to form a plurality of independent substrates, each of which has an LED light-emitting structure disposed thereon, comprises: The focal point is located on the surface of the common substrate at a side away from the LED light emitting structure, so as to form a plurality of grooves on the surface of the common substrate at a side away from the LED light emitting structure; A pressure is applied to the common substrate to form a plurality of independent substrates, each of which has a first smooth portion and a first rough portion stacked in layers.

6. The method for preparing the light-emitting unit according to claim 5, characterized in that: The thickness of the first smooth portion is greater than three times the thickness of the first rough portion.

7. The method for preparing a light-emitting unit according to claim 2, characterized in that: In the step of laser cutting the common substrate to form a plurality of independent substrates, each of which is provided with one of the LED light-emitting structures, the side walls of the independent substrates are located outside the side walls of the LED light-emitting structures; In the step of forming a reflective film, wherein the reflective film covers the surface of each independent substrate away from the LED light-emitting structure and the side wall of each independent substrate, the reflective film also covers the surface of each independent substrate close to the LED light-emitting structure.

8. The method for preparing a light-emitting unit according to claim 1, characterized in that: The step of forming a reflective film, wherein the reflective film covers a surface of each of the independent substrates on a side away from the LED light-emitting structure and a side wall of each of the independent substrates comprises: Using an atomic layer deposition method, at a temperature of 150° C. to 200° C., a precursor of the first reflective layer and a precursor of the second reflective layer are sequentially released into a film forming chamber to form a first reflective layer and a second reflective layer stacked in sequence on the side wall of each of the independent substrates; The precursor of the first reflective layer includes a mixture of tantalum ethoxide and water, and the precursor of the second reflective layer includes a mixture of trimethylaluminum and water.

9. A light emitting unit, characterized in that: The light-emitting unit is prepared by the method for preparing the light-emitting unit according to any one of claims 1 to 8.

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