A red light display chip and preparation method, and light-emitting electronic component

Abstract

The present application belongs to the field of display chips, and specifically discloses a red light display chip and a preparation method, and a light-emitting electronic component. The red light display chip provided by the present application has a vertical light-emitting structure, and the arc structure formed by the processed cathode metal and the subsequently prepared microlens meet specific conditions and can form a matching optical system. In addition, the present application also provides a light-emitting electronic component made using the above-mentioned red light display chip. The present application prepares a common cathode red light display chip with a vertical structure, so that the cathode metal not only provides a power supply link as the cathode of the light-emitting chip, but also plays a structuring function, and the arc-shaped surface of the cathode metal reflects the light emitting path of part of the light, so that the cathode metal can cooperate with the microlens structure provided by the present application to achieve collimated emission of light and improve the light emission efficiency.

Description

Technical Field

[0001] The present application belongs to the field of display chips, and specifically relates to a red light display chip and a preparation method, and a light-emitting electronic component. Background Art

[0002] Traditional red light Micro LEDs face major technical bottlenecks in terms of light efficiency due to their high surface recombination rate and serious non-radiative recombination on the side walls. It is a huge technical challenge for red light Micro LEDs below 10μm to achieve high light output efficiency. A large number of surface optical structures are used to improve the light output effect of red light LEDs. Adding a microlens structure to the light output surface can improve the light divergence angle and improve the light output efficiency. However, small-sized microlenses are generally defined by photolithography, and it is difficult to achieve high-quality sidewall uniformity and smoothness. There will inevitably be differences in the light-emitting effect of a single pixel, which is not conducive to the realization of high-precision pixels. The convex microlens has limited collimation effect on Lambertian luminous bodies with relatively large areas, and cannot achieve complete collimation. The distance between microlenses is often small, and there is a lack of light-blocking units, so light will still form crosstalk in several adjacent lens units. Summary of the invention

[0003] The purpose of this application is to solve the deficiencies of the prior art and provide a red light display chip and a preparation method, and a light-emitting electronic component, specifically adopting the following technical solutions:

[0004] On the one hand, the present application provides a method for preparing a red light display chip, comprising the following steps:

[0005] An epitaxial wafer is prepared, which includes a substrate, an N-GaN layer, a light-emitting area, and a P-GaN layer from bottom to top; an ITO layer and an anode metal are prepared on the epitaxial wafer in sequence, and then the anode metal is patterned and then etched to form deep grooves reaching the N-GaN layer; the deep grooves are filled to separate the light-emitting area, the epitaxial wafer is flipped to bond the epitaxial wafer to the driver chip, the substrate is peeled off, the N-GaN layer is etched to form a groove, and then a cathode metal is prepared on the N-GaN layer, the cathode metal is processed to prepare an arc structure, a microlens is prepared in the arc structure, and a red light display chip is obtained by packaging.

[0006] In some preferred implementations, during the process of etching to form the grooves, the etching solution used includes at least one of a KOH solution and a TMAH solution.

[0007] In some preferred implementations, the patterning method includes photolithography.

[0008] In some preferred implementations, the thickness of the cathode metal is 2 μm-3 μm.

[0009] In some preferred embodiments, the method of cathode metal processing includes wet etching.

[0010] In some preferred implementations, the method for preparing the microlens comprises an inkjet printing method, the microlens material comprises a photocurable transparent polymer material, and the refractive index of the microlens material at the red light wavelength is 1.5-1.6.

[0011] On the one hand, the present application also provides a red light display chip manufactured by the above-mentioned manufacturing method.

[0012] In some preferred implementations, the arc-shaped structure is an arc-shaped or quasi-arc-shaped reflective cup, the curvature coefficient of the reflective cup is less than 0.5; and the diameter of the cup mouth of the reflective cup is greater than the diameter of the cup bottom of the reflective cup.

[0013] In some preferred implementations, the microlens satisfies the following conditions:

[0014] The convex surface of the microlens is an arc, and its radius is r; the focal length of the microlens is f; the central thickness of the microlens is h; the refractive index of the material of the microlens at the red wavelength is n; the microlens meets the following conditions:

[0015] f = r / (n-1) and (1 / 4) × r <h<(1 / 2)× r 。

[0016] On the other hand, the present application also provides a light-emitting electronic component including the above-mentioned red light display chip.

[0017] The beneficial effects of the present application are as follows: the present application prepares a common cathode red light display chip with a vertical structure, so that the cathode metal not only provides a power supply connection as the cathode of the light-emitting chip, but also plays a structuring function, and the arc-shaped surface of the cathode metal reflects part of the light emission path, so that the cathode metal can cooperate with the microlens structure provided by the present application to achieve collimated emission of light and improve the light emission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a schematic structural diagram of a red light display chip provided by the present application;

[0019] Figure 2 Shown is a schematic diagram of an epitaxial wafer preparation stage in a method for preparing a red light display chip provided in the present application;

[0020] Figure 3 Shown is a schematic diagram of an epitaxial wafer etching stage in a method for preparing a red light display chip provided by the present application;

[0021] Figure 4 Shown is a schematic diagram of an epitaxial wafer injection stage in a method for preparing a red light display chip provided in the present application;

[0022] Figure 5 The figure shows a schematic diagram of the epitaxial wafer inversion docking stage in a red light display chip preparation method provided by the present application;

[0023] Figure 6 The figure shows a schematic diagram of the epitaxial wafer substrate peeling stage in a method for preparing a red light display chip provided by the present application;

[0024] Figure 7 Shown is a schematic diagram of the N-GaN layer processing stage in a method for preparing a red light display chip provided in the present application;

[0025] Figure 8 Shown is a schematic diagram of a cathode metal preparation stage in a method for preparing a red light display chip provided in the present application;

[0026] Fig. 9 Shown is a schematic diagram of a cathode metal processing stage in a method for preparing a red light display chip provided in the present application;

[0027] Fig.10 Shown is a schematic diagram of a top view structure of a red light display chip provided by the present application;

[0028] Fig.11 Shown is a schematic diagram of the optical path design of a red light display chip provided in this application;

[0029] Fig.12 Shown is a schematic diagram of the structure of a red light display chip provided in this application.

[0030] In the attached figure:

[0031] 10-anode metal; 11-ITO layer; 12-P-GaN layer; 13-light-emitting area; 14-N-GaN layer; 15-substrate; 16-isolation structure; 17-bonding interface; 18-CMOS; 19-groove; 20-cathode metal; 21-reflective cup; 22-microlens. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present application, so as to fully understand the purpose, scheme and effect of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The same reference numerals used throughout the drawings indicate the same or similar parts.

[0033] The present application provides a red light display chip and a preparation method, and a light-emitting electronic component. The red light display chip provided in the present application is a Micro LED display chip, which is mainly used to solve at least one problem existing in traditional red light Micro LED chips in the prior art.

[0034] In the prior art, traditional red light Micro LED display chips not only have a high surface recombination rate, but also have a serious sidewall non-radiative recombination phenomenon, which makes traditional red light Micro LED display chips have a major technical bottleneck in terms of light efficiency.

[0035] On the one hand, the surface recombination rate has a huge impact on the performance of the red light Micro LED display chip; because during the operation of the red light Micro LED display chip, electrical energy will be converted into light energy. When the surface recombination rate of the surface structure of the red light Micro LED display chip is too high, a large number of carriers will recombine on the surface instead of in the light-emitting area 13, which will reduce the utilization rate of the carriers, resulting in a decrease in the number of carriers reaching the light-emitting area 13, reducing the recombination rate in the light-emitting area 13, and further reducing the luminous efficiency.

[0036] Not only that, the high surface recombination rate will cause more energy to be dissipated in the form of heat energy instead of being converted into light energy, which will increase the thermal load of the red light Micro LED display chip, causing the device temperature to rise and affecting the stability and life of the device.

[0037] Therefore, controlling and optimizing the surface recombination rate is crucial to improving the luminescence performance, energy efficiency, reliability and life of the red light Micro LED display chip. In this application, a vertically structured red light Micro LED display chip is prepared, the N electrode is designed as a common cathode metal 20 grid, and a continuous metal grid is used to achieve electrical interconnection, thereby improving the conductivity of the red light Micro LED display chip, thereby having better ability to handle current expansion and electrical power performance.

[0038] On the other hand, the non-radiative recombination phenomenon of red light Micro LED display chips will lead to carrier accumulation, causing carriers to accumulate on the side walls in small-sized red light Micro LED display chips, thereby causing edge effects and size effects, reducing the hole injection efficiency and increasing the leakage current, thereby affecting the light extraction efficiency.

[0039] The present application also uses a mask etching technology in the process of preparing a vertically structured red light Micro LED display chip to etch the light-emitting region 13. During the etching process, the light-emitting region 13 is repaired, thereby repairing the damage to the epitaxial surface, reducing the recombination on the edge surface of the N region, and repairing the lattice disorder on the side wall surface, thereby improving the side wall damage and avoiding the enrichment of impurity ions at the side wall to form non-radiative recombination.

[0040] This application not only improves the problems existing in traditional red light Micro LED display chips at the microscopic level, but also innovates in the light output structure.

[0041] The present application prepares an arc structure on the cathode metal 20 to make it a reflective cup 21 for reflecting light, and prepares a microlens 22 structure that matches it on the outer surface of the light-emitting area 13 to form a common cathode metal 20 grid, so that the vertically structured red light Micro LED display chip can improve the luminous efficiency while reducing light divergence, achieving the convergence and collimation of the light source and improving the light output efficiency.

[0042] In the implementation scheme provided in the present application, a commercial InGaN red light epitaxial wafer is selected, and its light emission wavelength is 640nm, but the claims of this scheme are not limited to the use of this red light epitaxial wafer.

[0043] The present application provides a red light display chip and a preparation method, and a light-emitting electronic component, wherein the specific preparation method of the red light display chip includes:

[0044] Combination Figure 1-Figure 8 The present application uses a commercial InGaN red light epitaxial wafer, the emission wavelength of which is 640nm. The InGaN epitaxial wafer includes a substrate 15, an N-GaN layer 14, a light-emitting area 13, and a P-GaN layer 12 from bottom to top; an ITO layer 11 and an anode metal 10 are sequentially prepared on the epitaxial wafer, and then the anode metal 10 is patterned, and then a deep groove is etched to reach the N-GaN layer 14; the deep groove is filled to separate the light-emitting area 13, the epitaxial wafer is flipped to bond the epitaxial wafer to the driver chip, the substrate 15 on the top layer of the epitaxial wafer is peeled off, the N-GaN layer 14 is etched to form a groove 19, and then a cathode metal 20 is prepared on the N-GaN layer 14, the cathode metal 20 is processed to prepare an arc structure, a microlens 22 is prepared in the arc structure, and a red light display chip is obtained by packaging.

[0045] Combination Figure 2In this embodiment, the ITO layer 11 is first grown on the InGaN epitaxial wafer, so that an ITO layer 11 is grown on the epitaxial wafer. The ITO layer 11 is a transparent conductive material that can collect and transmit electrons, so that the vertical structure red light display chip provided by the present application has excellent performance. First, the ITO layer 11 is prepared on the P-GaN layer 12. The ITO layer 11 is tightly combined with the P-GaN layer 12 to form a good ohmic contact, improve the surface flatness of the P-GaN layer 12, and enhance the conductivity of the P-GaN layer 12. At the same time, the ITO layer 11 also has a surface passivation function, which can passivate the surface of the P-GaN and reduce the surface recombination rate of the P-GaN, thereby improving the internal quantum efficiency; the ITO layer 11 also has good light transmittance and a certain degree of reflection performance, which makes the ITO layer 11 not only improve the internal quantum efficiency but also use the ability to reflect light. After the epitaxial wafer is subsequently flipped, it can be used as the bottom material to realize the reflection of light energy, thereby reflecting the unextracted light back to the active area, thereby improving the light extraction efficiency.

[0046] After the ITO layer 11 is prepared, the anode metal 10 needs to be prepared. The anode metal 10 is an important light-emitting control junction link structure. Preparing the anode metal 10 on the ITO layer 11 can increase the contact rate, thereby improving the performance.

[0047] Combination Figure 3 After the preparation of the anode metal 10 is completed, the epitaxial wafer is patterned to define the etching range and protect the non-processed part. The epitaxial wafer is then etched to prepare a deep through hole that penetrates the anode metal 10, the ITO layer 11, the P-GaN layer 12 and the light-emitting area 13. This deep through hole directly reaches the N-GaN layer 14. During the etching process, KOH etching solution is used to treat the GaN surface so that the outer surface damage during the processing process is repaired, thereby removing the damaged layer of the side wall microstructure, thereby improving the luminous efficiency.

[0048] Combination Figure 4 After the deep grooves are etched, they need to be filled to separate the light-emitting areas 13 so that each light-emitting area 13 is separated to form an independent light-emitting unit, so that the light emitted by each separated light-emitting area 13 does not interfere with each other, thus avoiding light crosstalk.

[0049] Combination Figure 5 After completing the separation of the light-emitting area 13, the entire epitaxial wafer needs to be flipped over so that it can be bonded to the driver chip (ie, CMOS 18).

[0050] Combination Figure 6 After the bonding between the epitaxial wafer and the driver chip is completed, the substrate 15 located at the top layer of the epitaxial wafer needs to be peeled off for subsequent processing.

[0051] Combination Figure 7-8 , after the substrate 15 is peeled off, at this time, the exposed N-GaN layer 14 needs to be processed to form a groove 19, and then the cathode metal 20 is prepared. At this time, the thickness of the cathode metal 20 needs to reach 2μm - 3μm. Preparing such a thick cathode metal 20 is to facilitate subsequent processing while taking into account the electrical conductivity.

[0052] Combined with Figure 1 and Figure 9-12 , after the cathode metal 20 is prepared, wet etching needs to be used to perform isotropic etching on the cathode metal 20 until the light-emitting surface of the N-GaN is exposed. The side wall of the etched metal presents an arc shape, which is the arc structure.

[0053] After the arc structure is processed, inkjet printing technology and thermal reflow technology need to be used to prepare the microlens 22 in the pixel area formed by the arc structure. At this time, the material for preparing the microlens 22 can be PMMA negative photoresist with a refractive index of 1.5.

[0054] In some implementation cases, the material for preparing the microlens 22 can be negative photosensitive polymers such as SU-8 2000, SU-8 3000, ma-N, etc. with a refractive index in the range of 1.5 - 1.6.

[0055] During the process of preparing the arc structure and the microlens 22, in order to improve the light-emitting performance of the light-emitting surface at the bottom of the cross-section of the cathode metal 20 area, precise control needs to be performed on the arc structure prepared from the cathode metal 20, so that the surface parameters of the reflective cup 21 of the prepared arc structure are consistent with the optical parameters of the microlens 22 structure to be prepared subsequently. As a result, when the light emitted from the light-emitting surface is refracted by the microlens 22 and then irradiates onto the arc structure of the cathode metal 20, the reflection that occurs is precisely controllable. Therefore, the red light display chip provided by this application has excellent luminous efficiency and high collimation. Therefore, the surface coefficient of the arc structure of the cathode metal 20 is less than 0.5.

[0056] Combined with the Fig.11 schematic diagram of the optical path design of a red light display chip provided, and the Fig.12 schematic diagram of the structure annotation of a red light display chip provided;

[0057] Among them, the arc structure forms a reflective cup 21. The diameter of the cup mouth of the reflective cup 21 is B, the diameter of the cup bottom is A, the height of the reflective cup 21 is H, and the radius of the arc structure is R; in some implementation cases, the following relationship is satisfied: A < B and A = H = R.

[0058] The convex surface of the microlens 22 is an arc, and its radius is r; the focal length of the microlens 22 is f; the central thickness of the microlens 22 is h; the refractive index of the material of the microlens 22 at the red wavelength is n; the microlens 22 satisfies the following conditions: f=r / (n-1) and (1 / 4)× r <h<(1 / 2)× r 。

[0059] After the above structure is prepared, it is packaged to obtain the red light display chip provided by the present application, and its structural diagram is shown in FIG. Figure 1 As shown, the top view of the structure is as follows Fig.10 shown.

[0060] The red light display chip provided in this application can be applied to various light-emitting electronic components.

[0061] Although the description of the present application has been quite detailed and specifically describes several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the attached claims in view of the prior art, thereby effectively covering the intended scope of the present application. In addition, the above describes the present application with the embodiments foreseeable by the inventor, the purpose of which is to provide a useful description, and those non-substantial changes to the present application that have not yet been foreseen may still represent equivalent changes to the present application.

Claims

1. A method for preparing a red light display chip, characterized in that: The following steps are involved: An epitaxial wafer is prepared, wherein the epitaxial wafer includes a substrate, an N-GaN layer, a light-emitting area, and a P-GaN layer in order from bottom to top; an ITO layer and an anode metal are sequentially prepared on the epitaxial wafer, and then the anode metal is patterned, and then a deep groove is etched to form a deep groove reaching the N-GaN layer; the deep groove is filled to separate the light-emitting area, the epitaxial wafer is turned over to bond the epitaxial wafer to a driving chip, the substrate is peeled off, the N-GaN layer is etched to form a groove, and then a cathode metal is prepared on the N-GaN layer, the cathode metal is processed to prepare an arc structure, a microlens is prepared in the arc structure, and the red light display chip is packaged to obtain the red light display chip; The arc-shaped structure is a reflective cup in an arc shape or a shape similar to an arc shape, and the curvature coefficient of the reflective cup is less than 0.5; and / or the arc-shaped structure is a reflective cup in an arc shape or a shape similar to an arc shape, and the diameter of the cup mouth is greater than the diameter of the cup bottom; The convex surface of the microlens is an arc, and its radius is r; the focal length of the microlens is f; the central thickness of the microlens is h; the refractive index of the material of the microlens at the red wavelength is n; the microlens meets the following conditions: f=r / (n-1) and (1 / 4)×r < h < (1 / 2)×r.

2. The method for preparing a red light display chip according to claim 1, characterized in that: In the process of etching to form the groove, the etching solution used includes at least one of a KOH solution and a TMAH solution.

3. The method for preparing a red light display chip according to claim 1, characterized in that: The patterning method includes photolithography.

4. The method for preparing a red light display chip according to claim 1, characterized in that: The thickness of the cathode metal is 2 μm-3 μm.

5. The method for preparing a red light display chip according to claim 1, characterized in that: The method of cathode metal processing includes wet etching.

6. The method for preparing a red light display chip according to claim 1, characterized in that: The method for preparing the microlens comprises an inkjet printing method, the material of the microlens comprises a transparent polymer material that can be photocured, and the refractive index of the material of the microlens at the wavelength of red light is 1.5-1.

6.

7. A red light display chip, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

8. A light-emitting electronic component, characterized in that: Including the red light display chip as described in claim 7.

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