Preparation method of LED chip and LED chip

Abstract

The application relates to the technical field of LED chip preparation, and discloses a preparation method of an LED chip and the LED chip. The preparation method comprises the following steps: providing an LED wafer, wherein the LED wafer comprises a growth substrate, a light-emitting structure and an electrode layer; providing a support substrate; bonding the electrode layer to the support substrate; removing the growth substrate so that the light-emitting structure is exposed; providing a color conversion structure; bonding the color conversion structure to the light-emitting structure; and removing the support substrate to form an LED chip. The color conversion structure is bonded to the light-emitting structure of the LED wafer, so that the finally obtained LED has the color conversion function; the obtained LED chip is used to replace the existing red light LED chip to be applied to a small-pitch or micro-pitch LED display screen, the complex process in the preparation of the flip red light LED chip is omitted, the production yield is effectively improved, and the cost is reduced. Meanwhile, the LED prepared by the application has high reliability and can meet the application requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED chip preparation, and particularly relates to a preparation method of an LED chip and the LED chip. BACKGROUND

[0002] LED (Light Emitting Diode) chips are widely used in various fields and places, such as indoor and outdoor advertising screens, conference centers and command centers, due to their good energy-saving effect and high brightness.

[0003] Generally, an LED display screen is seamlessly spliced into a large-size display screen by a certain number of small-size display screen modules. One of the common manufacturing methods of small-pitch display screen modules is Chip On Board (COB). In the process of manufacturing small-pitch LED display screens by using the COB method at present, the chip used is a flip Mini LED chip. In addition, in order to realize full-color display, RGB three kinds of chips, i.e., red light LED chips, green light LED chips and blue light LED chips, are needed. In the prior art, the green light LED chip and the blue light LED chip made of gallium nitride are mature technology, and the manufacturing process is relatively simple. However, the red light LED chip is a quaternary LED, and its substrate is an opaque GaAs substrate. Therefore, the red light wafer needs to be bonded to a sapphire substrate first and then the GaAs substrate is removed. The process is relatively complex, and the removal of the GaAs substrate is easy to cause damage to the light-emitting structure of the red light wafer. Therefore, the preparation efficiency and yield of the current red light LED chip are low, which leads to high cost. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a preparation method of an LED chip and the LED chip, which solves the problem that the yield of the flip red light LED chip is low and the cost is high in the prior art, and thus the application requirements cannot be met.

[0005] To achieve the above object, the present application provides the following technical solutions:

[0006] A preparation method of an LED chip, comprising:

[0007] providing an LED wafer, the LED wafer comprising a growth substrate, a light-emitting structure and an electrode layer;

[0008] providing a support substrate;

[0009] bonding the electrode layer to the support substrate;

[0010] removing the growth substrate so that the light-emitting structure is exposed;

[0011] providing a color conversion structure;

[0012] bonding the color conversion structure to the light emitting structure;

[0013] removing the support substrate to form the LED.

[0014] Optionally, the removing the growth substrate comprises:

[0015] the growth substrate is removed using a wet etching process.

[0016] Optionally, the providing a color conversion structure comprises:

[0017] providing a transparent substrate, forming a porous structure layer having a plurality of pores on the transparent substrate, and filling the pores with a color conversion material.

[0018] Optionally, the growth substrate is a silicon substrate.

[0019] the transparent substrate is sapphire or silicon carbide, and the porous structure layer is gallium nitride.

[0020] Optionally, the bonding the color conversion structure to the light emitting structure comprises:

[0021] bonding the porous structure layer to the light emitting structure.

[0022] Optionally, before the bonding the color conversion structure to the light emitting structure, or after the removing the support substrate, the method further comprises:

[0023] thinning the transparent substrate.

[0024] Optionally, the support substrate has a bonding material layer formed thereon.

[0025] the bonding the electrode layer to the support substrate comprises:

[0026] bonding the electrode layer to the bonding material layer.

[0027] Optionally, the providing an LED wafer comprises: providing a growth substrate, and sequentially forming a light emitting structure and an electrode layer on the growth substrate to make the LED wafer.

[0028] the electrode layer comprises a first electrode and a second electrode having opposite polarities.

[0029] Optionally, the removing the support substrate to form the LED comprises:

[0030] removing the support substrate, and forming a plurality of independent LEDs after being cut.

[0031] The application further provides an LED chip prepared by the preparation method of the LED according to any one of the above.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] The application provides a preparation method of an LED chip and the LED chip. In the process of preparing the LED, the color conversion structure is bonded with the light emitting structure of the LED wafer, so that the obtained LED has the color conversion function. The obtained LED chip is used to replace the existing red light LED chip to be applied to a small-pitch or micro-pitch LED display screen, and the complex process in the preparation of the flip red light LED chip is omitted, the production yield is effectively improved, and the cost is reduced. Meanwhile, the LED prepared by the application has high reliability and can meet the application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0035] Figure 1 A flow chart of the preparation method of the LED chip provided by the application;

[0036] Figure 2 A structure schematic diagram of the LED wafer in the preparation method of the LED chip provided by the application;

[0037] Figure 3 A structure schematic diagram of the bonding of the LED wafer and the support substrate in the preparation method of the LED chip provided by the application;

[0038] Figure 4 A structure schematic diagram of the LED wafer and the support substrate after the bonding and the removal of the growth substrate in the preparation method of the LED chip provided by the application;

[0039] Figure 5 A structure schematic diagram of the color conversion structure in the preparation method of the LED chip provided by the application;

[0040] Figure 6 A structure schematic diagram of the bonding of the color conversion structure and the light emitting structure in the preparation method of the LED chip provided by the application;

[0041] Figure 7 A structure schematic diagram of the bonding of the color conversion structure and the light emitting structure after the removal of the support substrate in the preparation method of the LED chip provided by the application;

[0042] Figure 8 A structure diagram of an LED prepared by a preparation method of an LED chip provided by the present application;

[0043] Figure 9 A structure diagram of an LED chip provided by the present application.

[0044] In the above figures: 100, LED wafer; 101, growth substrate; 102, light emitting structure; 1031, first electrode; 1032, second electrode; 200, support substrate; 201, bonding material layer; 300, color conversion structure; 301, transparent substrate; 302, porous structure layer; 303, color conversion material. DETAILED DESCRIPTION

[0045] In order to make the objectives, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the embodiments described below are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0046] It should be understood that, in the description of the present application, the specific embodiments are only used to explain the present application, but not to limit the present application. Among them, the exemplary embodiments are described as processes or methods depicted by flowcharts; although the flowcharts describe the operations or steps of the processes in a certain order, many of the operations or steps can be implemented in parallel, concurrently or simultaneously, and the order of the operations can be rearranged. When the operations or steps are completed, the corresponding process can be terminated, and there can be additional steps not included in the drawings. The foregoing processes can correspond to methods, functions, procedures, subroutines, subprograms, etc., and the embodiments and features in the embodiments can be combined with each other without conflict.

[0047] The term "comprising" and its variants used in the present application are open and inclusive, i.e. "including but not limited to". The term "based on" is "at least partially based on". The technical solutions of the present application will be further illustrated below with reference to the drawings and through specific embodiments; it can be understood that, for the convenience of description, only the parts related to the present application are shown in the drawings, not all the structures.

[0048] With the continuous improvement of indoor display application technology, the current display application products such as projection, DLP (Digital Light Processing), LCD (Liquid Crystal Display), PDP (Plasma Display Panel) and the like cannot fully meet the market application requirements. There are still some defects in various aspects that cannot break through the development of technology. The full-color LED display screen overcomes many defects of the above products and has become the first choice for indoor and outdoor large-screen display, such as command center, outdoor advertising screen, conference center and the like.

[0049] LED chips have good energy-saving effect and high brightness, and are used in various industries of production and life. Generally, an LED display screen is seamlessly spliced into a large-size display screen by a certain number of small-size display screen modules. One of the common manufacturing methods of small-pitch display screen modules is Chip On Board (COB). In the process of manufacturing small-pitch LED display screens by using the COB method at present, the chip used is a flip Mini LED chip. In order to realize full-color display, red, green and blue Mini LED chips are needed. However, the LED chip in the prior art is usually made of gallium nitride-based material, and it is a mature technology to use gallium nitride-based chips to manufacture blue light LED and green light LED, which is simple to manufacture and use. However, the red light LED is a quaternary LED, and its substrate is opaque GaAs. If a flip red light LED is desired, the GaAs substrate needs to be removed after bonding the red light wafer to a sapphire substrate, which is a complex process. Especially in small-pitch or micro-pitch LED display screens, the cost of flip red light chips accounts for a large proportion, and the yield of this process is low. In addition, compared with GaN (gallium nitride) material, the AlInGaP epitaxial layer of red light is brittle and easy to break, and device failure often occurs due to peeling of the epitaxial film during use. The above process results in low yield and high cost of flip red light LED, and thus cannot meet the application requirements.

[0050] Therefore, it is necessary to provide a color-conversion LED chip suitable for small-pitch or micro-pitch LED display screens to replace the existing LED chip, especially the red light LED chip.

[0051] Please refer to Figures 1 to 9 The embodiment of the present application provides a preparation method of an LED chip, comprising:

[0052] S1, providing an LED wafer 100.

[0053] Please refer to Figure 2The LED wafer 100 comprises a growth substrate 101, a light emitting structure 102 and an electrode layer; wherein the growth substrate 101 is a silicon substrate; and the electrode layer comprises a first electrode 1031 and a second electrode 1032 with opposite polarities.

[0054] The step specifically comprises: providing a growth substrate 101, sequentially forming the light emitting structure 102 and the electrode layer on the growth substrate 101 to manufacture the LED wafer 100.

[0055] S2, providing a support substrate 200.

[0056] Please refer to Figure 3 In the embodiment, the support substrate 200 is provided with a bonding material layer 201.

[0057] The support substrate 200 can temporarily support the chip in the subsequent process to avoid the light emitting structure 102 from being broken.

[0058] S3, bonding the electrode layer to the support substrate 200.

[0059] Please refer to Figure 3 In the step, the electrode layer is bonded to the bonding material layer 201 when the electrode layer is bonded to the support substrate 200, so as to ensure the bonding effect between the LED wafer 100 and the support substrate 200.

[0060] S4, removing the growth substrate 101 to expose the light emitting structure 102.

[0061] In the step, the growth substrate 101 is removed to expose the light emitting surface of the light emitting structure 102.

[0062] Please refer to Figure 4 In the step, the growth substrate 101 is removed by using a wet etching process, which can avoid the damage to the light emitting structure 102 caused by the laser stripping growth substrate process of the conventional method, so as to ensure the light emitting efficiency of the light emitting structure 102.

[0063] S5, providing a color conversion structure 300.

[0064] Please refer to Figure 5 In the step, the color conversion structure 300 is provided by the following steps:

[0065] A transparent substrate 301 is provided; a porous structure layer 302 with a plurality of recess holes is formed on the transparent substrate 301; and a color conversion material 303 is filled in the recess holes.

[0066] The material of the transparent substrate 301 is sapphire or silicon carbide. When forming the porous structure layer 302 on the transparent substrate 301, a gallium nitride structure layer is first epitaxially formed on the transparent substrate 301, and a plurality of uniformly arranged recesses are made in the gallium nitride structure layer to form the porous structure layer 302. Specifically, the plurality of recesses can be formed in the gallium nitride structure layer by an electrochemical etching method. The gallium nitride structure layer is an n-type doped layer.

[0067] Specifically, the colored conversion material 303 is a quantum dot. The type of quantum dot can be selected according to actual needs. For example, by filling red quantum dots in the recesses, blue light can be converted into red light; by filling green quantum dots in the recesses, blue light can be converted into green light.

[0068] In addition, a photocurable colored conversion liquid can be selected. When filling the colored conversion material 303 in the recesses, the colored conversion liquid is injected into the recesses, and after photocuring, the colored conversion material 303 is fixed in the recesses.

[0069] S6, bonding the color conversion structure 300 to the light-emitting structure 102.

[0070] Please refer to Figure 6 In this step, the porous structure layer 302 is bonded to the light-emitting structure 102.

[0071] Specifically, in the color conversion structure 300, the recesses on the porous structure layer 302 are blind holes opened on the outer surface. When the color conversion structure 300 is bonded to the light-emitting structure 102, the light-emitting structure 102 is bonded to the outer surface of the porous structure layer 302, which can ensure the effectiveness and efficiency of color conversion.

[0072] S7, removing the support substrate 200 to form an LED chip.

[0073] Please refer to Figure 7 , Figure 8 In this step, after removing the support substrate 200, the obtained structure is cut to obtain a plurality of independent LED chips.

[0074] Please refer to Figure 9 In one of the embodiments of the present embodiment, before step S6: bonding the color conversion structure 300 to the light-emitting structure 102, it further includes: thinning the transparent substrate 301.

[0075] In another embodiment of the present embodiment, after step S7: removing the support substrate 200, it further includes: thinning the transparent substrate 301.

[0076] Since the finally formed LED chip has the structure layers in sequence including the transparent substrate 301, the color conversion structure 300, the light emitting structure 102 and the electrode layer, the light emitting effect of the LED chip can be improved by thinning the transparent substrate 301, and meanwhile, the supporting effect can be provided.

[0077] In the embodiment, the LED chip has certain structural strength by reserving the thinned transparent substrate 301, so that the prepared LED chip has appropriate thickness, and the LED chip can be transferred and applied to the LED display screen on the basis of the simple transfer technology in the prior art, thereby effectively improving the production efficiency of the LED display screen and improving the production yield.

[0078] Based on the foregoing embodiments, the application further provides an LED chip prepared by the method for preparing the LED chip as in the foregoing embodiments.

[0079] Specifically, the LED chip includes the transparent substrate 301, the color conversion structure 300, the light emitting structure 102 and the electrode layer.

[0080] The material of the transparent substrate 301 is sapphire or silicon carbide; the material of the porous structure layer 302 is a gallium nitride structure layer, and the porous structure layer 302 has a plurality of uniformly arranged recesses filled with the color conversion material 303.

[0081] Specifically, the color conversion material 303 is quantum dots, and the type of quantum dots can be selected according to actual needs. For example, by filling red quantum dots in the recesses, blue light can be converted into red light; by filling green quantum dots in the recesses, blue light can be converted into green light.

[0082] Based on the foregoing embodiments, the application bonds the color conversion structure 300 with the light emitting structure 102 of the LED wafer 100, so that the finally obtained LED chip has the color conversion function, the complex process for preparing the flip-chip red LED chip is omitted, the production yield is effectively improved, and the cost is reduced. The obtained LED chip is used to replace the existing red LED chip to be applied to the small-pitch or micro-pitch LED display screen, so that the product cost is reduced, the production efficiency is improved, and the application requirements are met.

[0083] The above embodiments are only used to illustrate the technical solutions of the application, but not limit the application; although the application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and the modification or replacement does not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A method for fabricating an LED chip, characterized in that, include: An LED wafer is provided, the LED wafer comprising a growth substrate, a light-emitting structure, and an electrode layer; Provide a supporting substrate; The electrode layer is bonded to the supporting substrate; Remove the growth substrate to expose the light-emitting structure; Provides a single-color conversion structure; The color conversion structure is bonded to the light-emitting structure; Remove the supporting substrate to form an LED chip; The provided single-color conversion structure includes: A transparent substrate is provided, and a porous structure layer with multiple recesses is formed on the transparent substrate, wherein a color conversion material is filled in the recesses; The porous structure layer is made of gallium nitride, and the porous structure is formed by electrochemical etching of the gallium nitride structure layer, which is an n-type doped layer. The growth substrate is a silicon substrate; The transparent substrate is made of sapphire or silicon carbide, and the porous structure layer is made of gallium nitride. The removal of the growth substrate includes: The growth substrate was removed using a wet etching process.

2. The method for preparing an LED chip according to claim 1, characterized in that, The step of bonding the color conversion structure to the light-emitting structure includes: The porous structure layer is bonded to the light-emitting structure.

3. The method for preparing an LED chip according to claim 1, characterized in that, Before bonding the color conversion structure to the light-emitting structure, or after removing the supporting substrate, the method further includes: Thinning of the transparent substrate.

4. The method for preparing an LED chip according to claim 1, characterized in that, A bonding material layer is formed on the supporting substrate; The step of bonding the electrode layer to the supporting substrate includes: The electrode layer is bonded to the bonding material layer.

5. The method for preparing an LED chip according to claim 1, characterized in that, The provision of an LED wafer includes: providing a growth substrate, and sequentially forming a light-emitting structure and an electrode layer on the growth substrate to fabricate an LED wafer; The electrode layer includes a first electrode and a second electrode with opposite polarities.

6. The method for preparing an LED chip according to claim 1, characterized in that, The process of removing the support substrate to form an LED includes: The supporting substrate is removed, and after cutting, multiple independent LED chips are formed.

7. An LED chip, characterized in that, It is made by the method of preparing the LED chip according to any one of claims 1 to 6.

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