Light-emitting structure and preparation method thereof
By directly preparing the lens on the luminescent chip wafer of the Micro-LED display screen and cutting it into a single grain to bond with the driver chip, the problem of large alignment deviation of the single chip bonding process in the prior art is solved, and a light emitting structure preparation with higher quality and lower process difficulty is achieved.
Patent Information
- Application Number
- CN202510584326.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-07
- Publication Date
- 2025-06-24
AI Technical Summary
In the preparation of existing Micro-LED displays within the small and micro size range, the single-chip bonding process has high requirements for equipment and process control, and it is easy to cause excessive bonding and bonding bias, resulting in poor product quality and poor performance.
The method of directly preparing lenses on the luminescent chip wafer is adopted, and then the wafer is cut into a single luminescent chip grain and bonded with the driver chip grain for single chip to simplify the process steps and reduce the process difficulty.
Through single chip bonding, the accumulation of alignment deviation is avoided, the quality and performance of the product is improved, the process difficulty is reduced, and the cost control is better.
Smart Images
Figure CN120201832A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and particularly to a light-emitting structure and a method for preparing the same. Background Art
[0002] The emerging Micro-LED display technology has been widely used due to its advantages such as high brightness, low power consumption, long lifespan, and high contrast. According to the screen size, Micro-LED displays are generally classified into several categories, such as small micro-size, small and medium-size, medium and large-size, large-size, and extra-large-size. Among them, small micro-size displays are generally prepared by a single (chip) bonding process. The single-chip bonding process has high requirements for equipment and process control, and it is very easy to have a large cumulative bonding alignment deviation. As a result, the quality of the final product may not be good and the performance may be poor. Summary of the Invention
[0003] The purpose of this application is to provide a light-emitting structure and a method for preparing the same, with relatively low process difficulty and good product quality.
[0004] To achieve the above object, this application provides the following technical solutions:
[0005] This application provides a method for preparing a light-emitting structure, and the preparation method includes:
[0006] Preparing a light-emitting chip wafer, where the light-emitting chip wafer includes a substrate and an epitaxial structure above the substrate, and the epitaxial structure includes a U-GaN layer of the light-emitting chip;
[0007] Removing the substrate to expose the U-GaN layer, and preparing a lens with the U-GaN layer;
[0008] Cutting the light-emitting chip wafer into light-emitting chip grains;
[0009] Separately preparing driving chip grains, and bonding the light-emitting chip grains and the driving chip grains to obtain the required light-emitting structure.
[0010] In one embodiment, removing the substrate to expose the U-GaN layer and preparing a lens with the U-GaN layer includes:
[0011] Separately providing a temporary substrate, spin-coating a temporary bonding adhesive on the temporary substrate, and bonding the temporary substrate and the light-emitting chip wafer;
[0012] Removing the substrate to expose the U-GaN layer;
[0013] Performing an etching process on the U-GaN layer to form a lens on the U-GaN layer.
[0014] In one embodiment, an etching process is performed on the U-GaN layer to form a lens on the U-GaN layer, including:
[0015] Apply a photoresist on the U-GaN layer and perform photolithography to obtain a patterned photoresist.
[0016] Then, perform a reflow on the patterned photoresist, and the photoresist deforms under heat to become hemispherical.
[0017] Next, use the hemispherical photoresist as a mask to perform dry etching on the U-GaN layer, so that the surface of the U-GaN layer finally also becomes hemispherical, forming a lens.
[0018] In one embodiment, after forming the lens, it further includes:
[0019] Apply a photoresist on the U-GaN layer, and the photoresist forms a blank area through a photolithography process, and the blank area is located outside the lens.
[0020] Deposit a reflective metal layer on the U-GaN layer, and the reflective metal layer is formed both on the photoresist and within the blank area.
[0021] Remove the photoresist and the reflective metal layer on the photoresist to form a protective sidewall.
[0022] In one embodiment, after preparing the lens with the U-GaN layer, it further includes:
[0023] Prepare a color conversion structure on the light-emitting chip wafer.
[0024] In one embodiment, after forming the protective sidewall, it further includes:
[0025] Prepare red quantum dots and green quantum dots on the lens, and the red quantum dots and the green quantum dots constitute a color conversion structure.
[0026] In one embodiment, the height of the protective sidewall is greater than the height of the lens.
[0027] In one embodiment, separately prepare driving chip dies, including:
[0028] Prepare a driving chip wafer.
[0029] Deposit an adhesion metal layer on the top metal of the driving chip wafer.
[0030] Deposit solder on the electrodes of the driving chip wafer.
[0031] Cut the driving chip wafer to obtain driving chip dies.
[0032] In one embodiment, bonding the light-emitting chip die and the driving chip die to obtain the desired light-emitting structure, including:
[0033] Performing reflow on the driving chip die, bonding the light-emitting chip die and the driving chip die to obtain the light-emitting structure.
[0034] This application also provides a light-emitting structure, which is prepared by the preparation method as described above.
[0035] Compared with the prior art, the technical solution of this application has the following beneficial effects:
[0036] For the light-emitting structure and its preparation method of this application, first directly prepare a lens on the light-emitting chip wafer, and finally cut the light-emitting chip wafer into individual light-emitting chip dies, and perform single-chip bonding on the light-emitting chip dies and the driving chip dies. There is only one single-chip bonding process throughout, and it is not easy to have cumulative deviation in alignment. The overall process difficulty is relatively low, which can ensure that the prepared light-emitting structure products have good quality and performance. Among them, preparing a lens on the light-emitting chip wafer means that the lens is directly formed on the light-emitting chip wafer by wafer-level technology; correspondingly, lenses are formed on each light-emitting chip at the same time, and alignment is relatively easy to be accurate, and the process difficulty is relatively low, which also improves the product quality.
[0037] This application directly prepares a lens using a U-GaN layer, without the need to use a bonding process and without considering the difficult problem of one-to-one alignment; directly preparing a lens using a U-GaN layer is carried out under wafer-level technology, and alignment is mainly ensured by photolithography technology. The accuracy of the photolithography technology itself is very high and can fully meet the alignment requirements of the light-emitting chip and the lens, so the product quality is good. Moreover, without depositing other materials separately to form the lens, on the one hand, the deposition step and deposition materials can be omitted, reducing costs. And the process required for this step of depositing other materials itself will have an adverse impact on the already formed structure and the structure to be formed later. This application avoids this impact and improves the product quality.
[0038] The color conversion structure of this application is not prepared separately in advance and then bonded to the light-emitting chip wafer, but is directly prepared on the light-emitting chip wafer, without considering the difficult problem of one-to-one alignment; directly preparing the color conversion structure on the light-emitting chip wafer is carried out under wafer-level technology, and alignment is mainly ensured by photolithography technology. The accuracy of the photolithography technology itself is very high and can fully meet the alignment requirements of the color conversion structure and the light-emitting chip, so the product quality is good. Moreover, when preparing the protective sidewalls for protecting red quantum dots and green quantum dots in the color conversion structure of this application, a reflective metal layer is used to form them. In this way, the protective sidewalls can also reflect light and emit as much light as possible, improving the overall light output brightness.
[0039] When the light-emitting chip die and the driving chip die are bonded with a single chip in this application, solder is deposited on the driving chip die and reflowed on the driving chip die. This can avoid the situation that if the solder is deposited on the light-emitting chip die, the lens and the color conversion structure (the lens and the color conversion structure are fabricated on the light-emitting chip die) may be affected by high temperature during reflow, further improving the product quality. Brief Description of the Drawings
[0040] To more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0041] Figure 1 It is a schematic flowchart of a method for fabricating a light-emitting structure provided in the first embodiment of this application;
[0042] Figures 2 - 8 Respectively Figure 1 It is a schematic structural diagram of the light-emitting structure formed by each step of the shown fabrication method. Detailed Description of the Embodiments
[0043] The following will clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of this application. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of this application. And in the following embodiments, each embodiment is described with emphasis. For parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0044] Please refer to Figure 1 As shown, the first embodiment of this application provides a method for fabricating a light-emitting structure, and the fabrication method includes:
[0045] Fabricate a light-emitting chip wafer, the light-emitting chip wafer includes a substrate and an epitaxial structure above the substrate, and the epitaxial structure includes a U-GAN layer of the light-emitting chip;
[0046] Remove the substrate to expose the U-GaN layer, and fabricate a lens with the U-GaN layer;
[0047] Cut the light-emitting chip wafer into light-emitting chip dice;
[0048] Separate the driving chip die, and bond the light-emitting chip die and the driving chip die to obtain the desired light-emitting structure.
[0049] First, briefly explain that the light-emitting chip wafer refers to a wafer containing multiple light-emitting chips, the light-emitting chip die refers to a die containing a single light-emitting chip, the driving chip die refers to a die containing a single driving chip, and the driving chip wafer to be described later refers to a wafer containing multiple driving chips. Naming with the light-emitting chip wafer and the driving chip wafer is mainly to more intuitively reflect that the corresponding steps are in the wafer-level process; naming with the light-emitting chip die and the driving chip die is mainly to more intuitively reflect that the corresponding steps are in the single-chip process. In addition, after preparing the lens on the light-emitting chip wafer and then preparing the color conversion structure, the light-emitting chip wafer already has the lens and the color conversion structure, and in the subsequent steps, the light-emitting chip wafer is still used for reference, mainly to simplify the description.
[0050] In the preparation method of the present application, first directly prepare the lens on the light-emitting chip wafer, and finally cut the light-emitting chip wafer into individual light-emitting chip dice, and perform single-chip bonding on the light-emitting chip dice and the driving chip dice. There is only one single-chip bonding process throughout, and the alignment is not prone to cumulative deviation. The overall process difficulty is relatively low, which can ensure that the prepared light-emitting structure product has good quality and performance. Among them, preparing the lens on the light-emitting chip wafer means that the lens is directly formed on the light-emitting chip wafer by using the wafer-level process; correspondingly, lenses are formed on each light-emitting chip at the same time, and the alignment is relatively easy to be accurate, and the process difficulty is relatively low, which also improves the product quality.
[0051] Of course, the light-emitting structure prepared by the above-mentioned preparation method does not yet have the full-color function. In another embodiment, after preparing the lens with the U-GaN layer, it further includes:
[0052] Prepare a color conversion structure on the light-emitting chip wafer.
[0053] In this way, the prepared light-emitting structure has a color conversion structure, and the full-color function is realized.
[0054] Next, a specific embodiment will be given and combined with Figures 2 - 7 , to elaborate in detail on the preparation method of the present application. Moreover, in this specific embodiment, the prepared light-emitting structure has the full-color function, that is, the preparation method includes preparing a color conversion structure on the light-emitting chip wafer. If the full-color function is not required, it is not necessary to prepare the color conversion structure on the light-emitting chip wafer.
[0055] In one embodiment, the specific method for preparing the light-emitting chip wafer may be the same as that in the existing solution, so it will not be elaborated herein. Through processes such as photolithography, etching, and coating, a microdisplay pixel array wafer with a total of N horizontal structures, that is, a light-emitting chip wafer, is finally obtained. It includes:
[0056] Provide a substrate with an epitaxial layer, or provide a substrate and then prepare an epitaxial layer on the substrate;
[0057] Please refer to Figure 2 As shown, for simplicity, Figure 2 only one light-emitting chip wafer and two of the light-emitting chips therein are schematically shown. The light-emitting chip wafer has a substrate 1 and an epitaxial structure above the substrate 1. The substrate 1 may come with an epitaxial layer when purchased externally, or the purchased substrate 1 may only have a single substrate structure, and then an additional epitaxial layer is prepared thereon during the preparation process of the present application. The substrate 1 may be a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The material of the epitaxial layer may be GaN. The light-emitting chips in the present application are prepared on the epitaxial layer (also called a buffer layer) on the substrate 1 to form an epitaxial structure to improve the product quality. Each light-emitting chip in the epitaxial structure includes: a U-GaN layer 2, an N-type layer 3 above the U-GaN layer 2, a multi-quantum well 4, a P-type layer 5, a current diffusion layer 6, an electrode 7 stacked in the middle position in sequence, a pad layer 8 on the periphery, and electrodes 7 above and below the pad layer 8. The electrode 7 below the pad layer 8 is in contact with the N-type layer 3, and a passivation layer 9 that wraps the foregoing structures and only exposes the pad layer 8 and the electrode 7 above. Among them, the N-type layer 3, the multi-quantum well 4, and the P-type layer 5 constitute the core light-emitting unit, and other structures are all used for electrical connection.
[0058] After the preparation of the light-emitting chip wafer is completed, the lens can be prepared. The lens can be pre-made and then bonded to the light-emitting chip wafer, or other materials can be deposited on the light-emitting chip wafer to form the lens. In the present application, the substrate is removed to expose the U-GaN layer, and then the lens is prepared from the material of the U-GaN layer. In one embodiment, removing the substrate and exposing the U-GaN layer to prepare the lens includes:
[0059] Provide a temporary substrate separately, spin-coat a temporary bonding adhesive on the temporary substrate, and bond the temporary substrate and the light-emitting chip wafer;
[0060] Remove the substrate;
[0061] Remove the substrate to expose the U-GaN layer;
[0062] Perform an etching process on the U-GaN layer to form a lens on the U-GaN layer.
[0063] Please refer toFigure 3 As shown, the temporary substrate 10 is mainly used to temporarily support the light-emitting chip wafer to remove the substrate 1. There is no substantial structure on it that needs to be aligned with the light-emitting chips on the light-emitting chip wafer. Therefore, when bonding, there is no need to consider the difficult problem of one-to-one alignment, and only overall alignment is required, and the process difficulty is very low. The temporary bonding glue 11 includes an adhesion layer 111 and a release layer 112 for easy removal in the subsequent process.
[0064] Please refer to Figure 4 As shown, it is the appearance after removing the substrate 1. For the sapphire substrate, the substrate 1 can be removed by laser lift-off, and for the silicon-based substrate, it can be removed by grinding or other methods.
[0065] Please refer to Figure 5 As shown, after removing the substrate 1, the U-GaN layer 2 is exposed. The material of the U-GaN layer 2 is GaN and is transparent. Therefore, in this application, the U-GaN layer 2 (part of its material) is directly used to prepare the lens. An etching process is performed on the U-GaN layer 2 to form a lens on the U-GaN layer 2, including: coating a photoresist on the U-GaN layer 2 for photolithography to obtain a patterned photoresist, and then performing a reflow on the patterned photoresist. The photoresist is deformed by heat to become hemispherical. Then, the U-GaN layer 2 is etched with the hemispherical photoresist as a mask. The etching is dry etching, and there is a different etching selectivity for the photoresist and the U-GaN layer 2, so that the surface of the U-GaN layer 2 finally also becomes hemispherical, which is the lens 12, and one lens 12 corresponds to one light-emitting chip, also called a microlens array.
[0066] In this application, the U-GaN layer is directly used to prepare the lens, without the need to adopt a bonding process, and there is no need to consider the difficult problem of one-to-one alignment; using the U-GaN layer to directly prepare the lens is carried out under wafer-level processes. The alignment is mainly ensured by the photolithography process, and the accuracy of the photolithography process itself is very high, which can fully meet the alignment requirements of the light-emitting chip and the lens 12. Therefore, the product quality is good. Moreover, no other materials are deposited separately to form the lens. On the one hand, the deposition step and deposition materials can be omitted, reducing costs. And the process required for the step of depositing other materials itself will have an adverse impact on the already formed structure and the structure to be formed later. For example, the high temperature and duration required for depositing other materials are unbearable for the temporary bonding glue 11 that bonds the temporary substrate 10 to support the light-emitting chip wafer.
[0067] After forming the lens 12 on the light-emitting chip wafer, a color conversion structure can be prepared on the light-emitting chip wafer. The color conversion structure can be pre-fabricated and then bonded to the light-emitting chip wafer, or the color conversion structure can be directly prepared on the light-emitting chip wafer. In this application, the color conversion structure is directly prepared on the light-emitting chip wafer. When directly preparing the color conversion structure on the light-emitting chip wafer, a protective sidewall for placing and protecting red and green quantum dots is required to prevent optical crosstalk between adjacent pixels (light-emitting chips). In one embodiment, after forming the lens, it further includes:
[0068] Coat a photoresist on the U-GaN layer, and the photoresist forms a blank area through a photolithography process. The blank area is located on the periphery of the lens;
[0069] Deposit a reflective metal layer on the U-GaN layer, and the reflective metal layer is formed both on the photoresist and within the blank area;
[0070] Remove the photoresist and the reflective metal layer on the photoresist to form a protective sidewall.
[0071] Please refer to Figure 6 As shown, coat a photoresist on the U-GaN layer 2, and form a blank area through a photolithography process. The blank area is located between adjacent lenses 12 and is also the position where the protective sidewall will be formed later. Then deposit a reflective metal layer on the U-GaN layer 2 (and on the photoresist). The reflective metal layer is formed both on the photoresist and within the blank area, and there is a height difference (step) between the reflective metal layer on the photoresist and the reflective metal layer within the blank area and they are not connected, that is, the photoresist is still exposed. Then remove the photoresist and the reflective metal layer on the photoresist, and use a photoresist cleaning solution to clean the photoresist. The photoresist being cleaned also takes away the reflective metal layer on the photoresist, thereby retaining the reflective metal layer within the blank area. The retained reflective metal layer serves as the protective sidewall 13 of the color conversion structure. Among them, in one embodiment, the height of the protective sidewall 13 is greater than the height of the lens 12 because the red and green quantum dots to be prepared later are prepared on the lens 12, so that the protective sidewall 13 can protect the red and green quantum dots.
[0072] After forming the protective sidewall 13, red and green quantum dots can be prepared on the lens. The red and green quantum dots constitute the color conversion structure, that is, the red and green quantum dots are filled in the position between the protective sidewalls 13. Please continue to refer to Figure 6 As shown, Figure 6Only schematically shown in the figure is that the lens 12 on one light-emitting chip is filled with green quantum dots 14 and not filled with red quantum dots, and the lens 12 on the other light-emitting chip remains in a vacant state. These can all be designed according to the actual different pixel light-emitting purpose requirements. Those skilled in the art are familiar with that corresponding different red quantum dots or green quantum dots 14 or left empty can be filled on the lens 12 of the corresponding different light-emitting chips according to different actual requirements. The filling of red quantum dots and green quantum dots can adopt photolithography technology or inkjet printing method.
[0073] In this way, the preparation of the color conversion structure is completed. The color conversion structure of this application is not prepared separately in advance and then bonded to the light-emitting chip wafer, but is directly prepared on the light-emitting chip wafer, without considering the difficult problem of one-to-one alignment; the direct preparation of the color conversion structure on the light-emitting chip wafer is carried out under wafer-level process, and the alignment is mainly ensured by photolithography technology, and the accuracy of the photolithography technology itself is very high, which can fully meet the alignment requirements of the color conversion structure and the light-emitting chip, so the quality of the product is better. Moreover, when preparing the protective sidewall 13 for protecting the red quantum dots and green quantum dots in the color conversion structure of this application, a reflective metal layer is used to form it. In this way, the protective sidewall 13 can also reflect light at the same time, emit the light as much as possible, and improve the overall light output brightness. If the protective sidewall is prepared with black glue, although it can also protect the red quantum dots and green quantum dots, the black glue has light absorption, which will absorb part of the light, thus reducing the overall light output brightness.
[0074] Please continue to refer to Figure 6 As shown, in an embodiment, a filter 15 is further provided above the red quantum dots and green quantum dots 14 to suppress stray light and improve the light output effect.
[0075] In an embodiment, after the preparation of the color conversion structure is completed, it further includes:
[0076] Bonding a transparent glass sheet on the color conversion structure;
[0077] Removing the temporary substrate.
[0078] Please refer to Figure 7 As shown, the transparent glass sheet 16 is bonded on the color conversion structure, which can be used to protect the color conversion structure and improve the product quality. Moreover, the transparent glass sheet 16 is mainly used to protect the color conversion structure as a whole, and there is no any substantial structure on it that needs to be aligned with the light-emitting chips on the light-emitting chip wafer. Therefore, when bonding, the difficult problem of one-to-one alignment does not need to be considered, and only overall alignment is required, and the process difficulty is very low. When bonding, glue 17 can be used for bonding to ensure stable bonding and improve the product quality. In a specific embodiment, the glue 17 can be a thermosetting glue or a thermoplastic glue. Note that the thickness of the glue should be as thin as possible to avoid increased crosstalk between pixels caused by excessive thickness.
[0079] After the transparent glass sheet 16 is stably bonded, the temporary substrate 10 can be removed. As described above, the temporary bonding adhesive 11 including the adhesion layer 111 and the release layer 112 is used when bonding the temporary substrate 10. At this time, the temporary substrate 10 can be easily debonded by removing the release layer 112, thereby removing the temporary substrate 10 and the adhesion layer 111. In order to ensure that the temporary substrate 10 and the temporary bonding adhesive 11 are removed completely, the light-emitting chip wafer can be cleaned after the temporary substrate 10 is removed. The cleaning uses an organic solution, and NMP (N-methyl-2-pyrrolidone), DMSO (dimethyl sulfoxide), IPA (isopropyl alcohol), acetone, etc. can be used.
[0080] After the light-emitting chip wafer is prepared, the light-emitting chip wafer is cut, and light-emitting chip grains can be formed by laser cutting and scribing, which is well known to those skilled in the art.
[0081] After introducing the preparation of the light-emitting chip grains above, the preparation of the driving chip grains will be introduced next. In one embodiment, the driving chip grains are prepared separately, including:
[0082] Prepare a driving chip wafer;
[0083] Deposit an adhesion metal layer on the top metal of the driving chip wafer;
[0084] Deposit solder on the electrodes of the driving chip wafer;
[0085] Cut the driving chip wafer to obtain driving chip grains.
[0086] Among them, the specific method used to prepare the driving chip wafer can be the same as the existing solution, and will not be elaborated herein. Please refer to Figure 8 As shown, the driving chip 18 in the prepared driving chip wafer can be a silicon-based CMOS chip or a glass-based TFT chip. During subsequent cutting, the silicon-based driving chip wafer can be thinned first and then cut, while the glass-based driving chip wafer can be directly cut. The material of the adhesion metal layer can be Ti, and the materials of the solder 19 can be In, Sn. Depositing the adhesion metal layer and the solder 19 on the driving chip wafer, that is, depositing the adhesion metal layer and the solder 19 on the driving chip grains, is for subsequent bonding with the light-emitting chip grains.
[0087] After obtaining the light-emitting chip grains and the driving chip grains, bonding can be carried out. In one embodiment, bonding the light-emitting chip grains and the driving chip grains to obtain the required light-emitting structure, including:
[0088] Reflow the driving chip die, bond the light-emitting chip die and the driving chip die to obtain the required light-emitting structure.
[0089] To bond the light-emitting chip die and the driving chip die, high-temperature reflow of the solder is required. In this application, the solder 19 is deposited on the driving chip wafer (driving chip die). Therefore, reflowing the driving chip die at this time can avoid the need to perform high-temperature pouring on the light-emitting chip die if the solder is deposited on the light-emitting chip wafer (light-emitting chip die). During reflow, the color conversion structure (the color conversion structure is prepared on the light-emitting chip die) may be affected by the high temperature, thus affecting the product quality. That is, in this application, the solder 19 is deposited on the driving chip wafer (driving chip die) for bonding and high-temperature reflow, which improves the product quality.
[0090] The light-emitting structure obtained in this application also belongs to the completion of a single-chip bonding process and is applicable to small and micro-sized display screens.
[0091] Finally, it should be added that the sequence of the steps in the preparation method of this application, unless clearly stated in this article, if not clearly stated, it means that it can be adjusted arbitrarily according to the actual situation.
[0092] The second embodiment of this application provides a light-emitting structure, which is prepared by the preparation method as described above. As described above, the light-emitting structure provided in this application is applicable to small and micro-sized display screens.
[0093] Compared with the prior art, the technical solution of this application has the following beneficial effects:
[0094] For the light-emitting structure and its preparation method of this application, a lens is directly prepared on the light-emitting chip wafer first, and finally the light-emitting chip wafer is cut into individual light-emitting chip dies. The light-emitting chip dies and the driving chip dies are bonded by a single-chip bonding process. There is only one single-chip bonding process throughout, and the alignment is not prone to cumulative deviation. The overall process difficulty is relatively low, which can ensure that the prepared light-emitting structure product has good quality and performance. Among them, the lens is prepared on the light-emitting chip wafer, that is, the lens is directly formed on the light-emitting chip wafer by a wafer-level process; correspondingly, lenses are formed on each light-emitting chip at the same time, and the alignment is relatively easy to be accurate, and the process difficulty is relatively low, which also improves the product quality.
[0095] In this application, a lens is directly fabricated using a U-GaN layer without the need for a bonding process, eliminating the need to consider the difficult issue of one-to-one alignment. The direct fabrication of the lens using the U-GaN layer is carried out under wafer-level processes, and alignment is mainly ensured by photolithography technology, which has a very high precision and can fully meet the alignment requirements between the light-emitting chip and the lens. Therefore, the product quality is good. Moreover, instead of depositing other materials separately to form the lens, on the one hand, the deposition steps and deposition materials can be omitted, reducing costs. Additionally, the processes used in the step of depositing other materials can have an adverse impact on both the already formed structure and the structure to be formed later. This application avoids this impact and improves the product quality.
[0096] The color conversion structure in this application is not pre-fabricated separately and then bonded to the light-emitting chip wafer. Instead, it is directly fabricated on the light-emitting chip wafer, eliminating the need to consider the difficult issue of one-to-one alignment. The direct fabrication of the color conversion structure on the light-emitting chip wafer is carried out under wafer-level processes, and alignment is mainly ensured by photolithography technology, which has a very high precision and can fully meet the alignment requirements between the color conversion structure and the light-emitting chip. Therefore, the product quality is good. Moreover, when forming the protective sidewalls for protecting the red quantum dots and green quantum dots in the fabrication of the color conversion structure in this application, a reflective metal layer is used. In this way, the protective sidewalls can also reflect light, maximizing the emitted light and enhancing the overall light output brightness.
[0097] When bonding the light-emitting chip die and the driving chip die as single chips in this application, the solder is deposited on the driving chip die and reflowed on the driving chip die. This can avoid the situation where, if the solder is deposited on the light-emitting chip die, the lens and the color conversion structure (prepared on the light-emitting chip die) may be affected by high temperature during reflow, further improving the product quality.
[0098] As described above, the above are only specific embodiments of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims. In addition, specific examples are used in the specification to elaborate on the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application, and the content of this specification should not be construed as a limitation to this application.
Claims
1. A method for preparing a light-emitting structure, characterized in that: The preparation method comprises: Prepare a light-emitting chip wafer, wherein the light-emitting chip wafer includes a substrate and an epitaxial structure above the substrate, wherein the epitaxial structure includes a U-GaN layer of the light-emitting chip; removing the substrate to expose the U-GaN layer, and preparing a lens using the U-GaN layer; Cutting the light-emitting chip wafer into light-emitting chip dies; A driving chip crystal grain is prepared separately, and the light-emitting chip crystal grain and the driving chip crystal grain are bonded to obtain a desired light-emitting structure.
2. The preparation method according to claim 1, characterized in that: The substrate is removed to expose the U-GaN layer, and a lens is prepared using the U-GaN layer, comprising: A temporary substrate is separately provided, and a temporary bonding adhesive is spin-coated on the temporary substrate to bond the temporary substrate to the light-emitting chip wafer; removing the substrate to expose the U-GaN layer; An etching process is performed on the U-GaN layer to form a lens on the U-GaN layer.
3. The preparation method according to claim 2, characterized in that: Performing an etching process on the U-GaN layer to form a lens on the U-GaN layer includes: Apply photoresist on the U-GaN layer and perform photolithography to obtain a patterned photoresist. Then the patterned photoresist is reflowed, and the photoresist is deformed by heat to become a hemispherical shape; Then, the U-GaN layer is dry-etched using the hemispherical photoresist as a mask, so that the surface of the U-GaN layer eventually becomes hemispherical, forming a lens.
4. The preparation method according to claim 2, characterized in that: After the lens is formed, it also includes: Applying photoresist on the U-GaN layer, wherein the photoresist is subjected to a photolithography process to form a blank area, and the blank area is located at the periphery of the lens; Depositing a reflective metal layer on the U-GaN layer, wherein the reflective metal layer is formed on the photoresist and in the blank area; The photoresist and the reflective metal layer on the photoresist are removed to form a protective sidewall.
5. The preparation method according to claim 4, characterized in that: After preparing the lens with the U-GaN layer, the method further comprises: A color conversion structure is prepared on the light-emitting chip wafer.
6. The preparation method according to claim 5, characterized in that: After forming the protective side wall, it also includes: Red quantum dots and green quantum dots are prepared on the lens, and the red quantum dots and the green quantum dots constitute a color conversion structure.
7. The preparation method according to claim 5, characterized in that: The height of the protective side wall is greater than the height of the lens.
8. The preparation method according to claim 1, characterized in that: A driver chip crystal is prepared separately, including: Preparing driver chip wafers; Depositing an adhesion metal layer on the top metal layer of the driver chip wafer; Depositing solder on electrodes of the driver chip wafer; The driver chip wafer is cut to obtain driver chip grains.
9. The preparation method according to claim 1, characterized in that: The light emitting chip crystal grain and the driving chip crystal grain are bonded to obtain the desired light emitting structure, including: The driving chip grain is reflowed, and the light-emitting chip grain and the driving chip grain are bonded to obtain the light-emitting structure.
10. A light emitting structure, characterized in that: The light-emitting structure is prepared by the preparation method according to any one of claims 1 to 9.